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  • Do I need a spatial index in my database?

    - by Sanoj
    I am designing an application that needs to save geometric shapes in a database. I haven't choosen the database management system yet. In my application, all database queries will have an bounding box as input, and as output I want all shapes within that database. I know that databases with a spatial index is used for this kind of application. But in my application there will not be any queries of type "give me objects nearby x/y" or other more complex queries that are useful in a GIS application. I am planning of having a database without a spatial index and have queries looking like: SELECT * FROM shapes WHERE x < max_x AND x > min_x AND y < max_y AND y > min_y And have an index on the columns x (double) and y (double). As long I can see, I don't really need a database with an spatial index, howsoever my application is close to that kind of applications. And even if I would like to have nearby queries, then I could create a big enough bounding box around that point. Or will this lead to poor performance? Do I really need a spatial database? And when is a spatial index needed?

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  • How to do a partial database backup and restore?

    - by Workshop Alex
    Simple problem. I'm working on a single SQL Server database which is shared between several offices. Each office has their own schema inside this database, thus dividing the database in logical pieces. (Plus one schema that is shared between multiple offices.) The database is stored on a dedicated server and we use a single database to keep the backup/restore procedure easier. The problem, however, is that the Accounting Office might be modifying a lot of data and then the Secretary Office makes a mistake which requires restoration of a backup. Unfortunately, restoring the backup means that Accounting will lose their recently added data. So, the alternative solution is by restoring the backup into a new database, remove the data from the old accounting schema and move the data for accounting only from the backup top the original database. This is the current solution and it's time-consuming and error-prone. So, is there a way to make backups of a single schema, possibly through code? And then to restore just that schema, probably through code too?

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  • VLOOKUP in Excel, part 2: Using VLOOKUP without a database

    - by Mark Virtue
    In a recent article, we introduced the Excel function called VLOOKUP and explained how it could be used to retrieve information from a database into a cell in a local worksheet.  In that article we mentioned that there were two uses for VLOOKUP, and only one of them dealt with querying databases.  In this article, the second and final in the VLOOKUP series, we examine this other, lesser known use for the VLOOKUP function. If you haven’t already done so, please read the first VLOOKUP article – this article will assume that many of the concepts explained in that article are already known to the reader. When working with databases, VLOOKUP is passed a “unique identifier” that serves to identify which data record we wish to find in the database (e.g. a product code or customer ID).  This unique identifier must exist in the database, otherwise VLOOKUP returns us an error.  In this article, we will examine a way of using VLOOKUP where the identifier doesn’t need to exist in the database at all.  It’s almost as if VLOOKUP can adopt a “near enough is good enough” approach to returning the data we’re looking for.  In certain circumstances, this is exactly what we need. We will illustrate this article with a real-world example – that of calculating the commissions that are generated on a set of sales figures.  We will start with a very simple scenario, and then progressively make it more complex, until the only rational solution to the problem is to use VLOOKUP.  The initial scenario in our fictitious company works like this:  If a salesperson creates more than $30,000 worth of sales in a given year, the commission they earn on those sales is 30%.  Otherwise their commission is only 20%.  So far this is a pretty simple worksheet: To use this worksheet, the salesperson enters their sales figures in cell B1, and the formula in cell B2 calculates the correct commission rate they are entitled to receive, which is used in cell B3 to calculate the total commission that the salesperson is owed (which is a simple multiplication of B1 and B2). The cell B2 contains the only interesting part of this worksheet – the formula for deciding which commission rate to use: the one below the threshold of $30,000, or the one above the threshold.  This formula makes use of the Excel function called IF.  For those readers that are not familiar with IF, it works like this: IF(condition,value if true,value if false) Where the condition is an expression that evaluates to either true or false.  In the example above, the condition is the expression B1<B5, which can be read as “Is B1 less than B5?”, or, put another way, “Are the total sales less than the threshold”.  If the answer to this question is “yes” (true), then we use the value if true parameter of the function, namely B6 in this case – the commission rate if the sales total was below the threshold.  If the answer to the question is “no” (false), then we use the value if false parameter of the function, namely B7 in this case – the commission rate if the sales total was above the threshold. As you can see, using a sales total of $20,000 gives us a commission rate of 20% in cell B2.  If we enter a value of $40,000, we get a different commission rate: So our spreadsheet is working. Let’s make it more complex.  Let’s introduce a second threshold:  If the salesperson earns more than $40,000, then their commission rate increases to 40%: Easy enough to understand in the real world, but in cell B2 our formula is getting more complex.  If you look closely at the formula, you’ll see that the third parameter of the original IF function (the value if false) is now an entire IF function in its own right.  This is called a nested function (a function within a function).  It’s perfectly valid in Excel (it even works!), but it’s harder to read and understand. We’re not going to go into the nuts and bolts of how and why this works, nor will we examine the nuances of nested functions.  This is a tutorial on VLOOKUP, not on Excel in general. Anyway, it gets worse!  What about when we decide that if they earn more than $50,000 then they’re entitled to 50% commission, and if they earn more than $60,000 then they’re entitled to 60% commission? Now the formula in cell B2, while correct, has become virtually unreadable.  No-one should have to write formulae where the functions are nested four levels deep!  Surely there must be a simpler way? There certainly is.  VLOOKUP to the rescue! Let’s redesign the worksheet a bit.  We’ll keep all the same figures, but organize it in a new way, a more tabular way: Take a moment and verify for yourself that the new Rate Table works exactly the same as the series of thresholds above. Conceptually, what we’re about to do is use VLOOKUP to look up the salesperson’s sales total (from B1) in the rate table and return to us the corresponding commission rate.  Note that the salesperson may have indeed created sales that are not one of the five values in the rate table ($0, $30,000, $40,000, $50,000 or $60,000).  They may have created sales of $34,988.  It’s important to note that $34,988 does not appear in the rate table.  Let’s see if VLOOKUP can solve our problem anyway… We select cell B2 (the location we want to put our formula), and then insert the VLOOKUP function from the Formulas tab: The Function Arguments box for VLOOKUP appears.  We fill in the arguments (parameters) one by one, starting with the Lookup_value, which is, in this case, the sales total from cell B1.  We place the cursor in the Lookup_value field and then click once on cell B1: Next we need to specify to VLOOKUP what table to lookup this data in.  In this example, it’s the rate table, of course.  We place the cursor in the Table_array field, and then highlight the entire rate table – excluding the headings: Next we must specify which column in the table contains the information we want our formula to return to us.  In this case we want the commission rate, which is found in the second column in the table, so we therefore enter a 2 into the Col_index_num field: Finally we enter a value in the Range_lookup field. Important:  It is the use of this field that differentiates the two ways of using VLOOKUP.  To use VLOOKUP with a database, this final parameter, Range_lookup, must always be set to FALSE, but with this other use of VLOOKUP, we must either leave it blank or enter a value of TRUE.  When using VLOOKUP, it is vital that you make the correct choice for this final parameter. To be explicit, we will enter a value of true in the Range_lookup field.  It would also be fine to leave it blank, as this is the default value: We have completed all the parameters.  We now click the OK button, and Excel builds our VLOOKUP formula for us: If we experiment with a few different sales total amounts, we can satisfy ourselves that the formula is working. Conclusion In the “database” version of VLOOKUP, where the Range_lookup parameter is FALSE, the value passed in the first parameter (Lookup_value) must be present in the database.  In other words, we’re looking for an exact match. But in this other use of VLOOKUP, we are not necessarily looking for an exact match.  In this case, “near enough is good enough”.  But what do we mean by “near enough”?  Let’s use an example:  When searching for a commission rate on a sales total of $34,988, our VLOOKUP formula will return us a value of 30%, which is the correct answer.  Why did it choose the row in the table containing 30% ?  What, in fact, does “near enough” mean in this case?  Let’s be precise: When Range_lookup is set to TRUE (or omitted), VLOOKUP will look in column 1 and match the highest value that is not greater than the Lookup_value parameter. It’s also important to note that for this system to work, the table must be sorted in ascending order on column 1! If you would like to practice with VLOOKUP, the sample file illustrated in this article can be downloaded from here. Similar Articles Productive Geek Tips Using VLOOKUP in ExcelImport Microsoft Access Data Into ExcelImport an Access Database into ExcelCopy a Group of Cells in Excel 2007 to the Clipboard as an ImageShare Access Data with Excel in Office 2010 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Quickly Schedule Meetings With NeedtoMeet Share Flickr Photos On Facebook Automatically Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition

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  • ODI - Creating a Repository in a 12c Pluggable Database

    - by David Allan
    To install ODI 11g into an Oracle 12c pluggable database, one way is to connect using a TNS string to the pluggable database service that is executing. For example when I installed my master repository, I used a JDBC URL such as; jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=mydbserver)(PORT=1522)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=PDBORA12.US.ORACLE.COM)))   I used the above approach rather than the host:port:sid which is a common mechanism many users use to quickly get up and going. Below you can see the repository creation wizard in action, I used the 11g release and simply installed the master and work repository into my pluggable database. Be wise with your repository IDs, I simply used the default, but you should be aware that these are key in larger deployments. The database in 12c has much more tighter control on users and resources, so just getting the user creating with sufficient resource on tablespaces etc in 12c was a little more work. Once you have the repositories up and running, then the fun starts using the 12c features. More to come.

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  • HealthSouth Upgrades to Oracle Database 11g Release 2 and Oracle RAC

    - by jenny.gelhausen
    HealthSouth Corporation, the nation's largest provider of inpatient rehabilitation services, has upgraded to Oracle Database 11g Release 2 underneath PeopleSoft Enterprise Human Capital Management. Additionally, HealthSouth improved the availability and performance of its Oracle PeopleSoft Enterprise applications and Enterprise Data Warehouse using Oracle Database 11g and Oracle Real Application Clusters. Oracle Database options -- Oracle Advanced Compression and Oracle Partitioning are key to HealthSouth's data lifecycle management practices and to utilizing storage systems more efficiently. Using compression on both partitioned as well as non-partitioned tables in its data warehouse, HealthSouth has seen a 4X storage reduction without any cost to performance. "Oracle Database 11g, along with Oracle Real Application Clusters, Advanced Compression and Partitioning, all lend themselves to delivering highly available, performant data warehousing," said Henry Lovoy, Data Manager, HealthSouth Corporation. Press Release var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-13185312-1"); pageTracker._trackPageview(); } catch(err) {}

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  • Join Oracle Database at Microsoft TechEd next week.

    - by Mandy Ho
    For the past nine years, Oracle has been a proud sponsor of Microsoft TechEd. TechEd is Mircosoft's premier technology conference for IT professionals and developers. This year, Oracle will demonstrate its latest database software for MS Windows, including Oracle Database 11g Enterprise and Express editions, TimesTen and MySQL.  Developers can learn how to develop .Net applications for the Oracle Database using the latest technologies, such as Entity Framework, LINQ and WCF Data Services. Attendees can also learn the new MySQL features enabling rapid installation, GUI Based application design, backup & recovery and much more within a Windows environment. Oracle will have a BOF (Birds of a Feather Session) on Tuesday, June 12, from 3:15 to 4:30. The topic will be Big Data: The Next Frontier for Innovation, Competition and Productivity. Otherwise you can visit Oracle everyday during the expo hours from Mon, June 11 to Thursday, June 14 at our booth #613. Talk to experts on TimesTen and MySQL on Windows and .NET. Also, we will have our 3D interactive demos on Oracle's engineered systems showing off Oracle Exadata, Database Appliance and more. Visit  http://northamerica.msteched.com/ for more information. 

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  • Flashback Database

    - by Sebastian Solbach (DBA Community)
    Flashback Database bezeichnet die Funktionalität der Oracle Datenbank, die Datenbank zeitlich auf einen bestimmten Punkt, respektive eine bestimmte System Change Number (SCN) zurücksetzen zu können - vergleichbar mit einem Rückspulknopf eines Kassettenrekorders oder der Rücksetztaste eines CD-Players. Mag dieses Vorgehen bei Produktivsystemen eher selten Einsatz finden, da beim Rücksetzten alle Daten nach dem zurückgesetzten Zeitpunkt verloren wären (es sei denn man würde dieser vorher exportieren), gibt es gerade für Test- oder Standby Systeme viele Einsatzmöglichkeiten: Rücksetzten des Systems bei fehlgeschlagenen Applikations-Upgrade Alternatives Point in Time Recovery (PITR) mit anschließendem Roll Forward (besonders geeignet bei Standby Systemen) Testdatenbank mit definiertem, reproduzierbaren Ausgangspunkt (z.B. für Real Application Testing) Datenbank Upgrade Test Einige bestehende Datenbank Funktionalitäten verwenden Flashback Database implizit: Snapshot Standby Reinstanziierung der Standby (z.B. bei Fast Start Failover) Obwohl diese Funktionalität gerade für Standby Systeme und Testsysteme bestens geeignet ist, gibt es eine gewisse Zurückhaltung Flashback Database einzusetzen. Eine Ursache ist oft die Angst vor zusätzlicher Last, die das Schreiben der Flashback Logs erzeugt, sowie der zusätzlich benötigte Plattenplatz. Dabei ist die Last im Normalfall relativ gering (ca. 5%) und auch der zusätzlich benötigte Platz für die Flashback Logs lässt sich relativ genau bestimmen. Ebenfalls wird häufig nicht beachtet, dass es auch ohne das explizite Einschalten der Flashback Logs möglich ist, einen garantieren Rücksetzpunkt (Guaranteed Restore Point kurz GRP) festzulegen, und die Datenbank dann auf diesen Restore Point zurückzusetzen. Das Setzen eines garantierten Rücksetzpunktes funktioniert in 11gR2 im laufenden Betrieb. Wie dies genau funktioniert, welche Unterschiede es zum generellen Einschalten von Flashback Logs gibt, wie man Flashback Database monitoren kann und was es sonst noch zu berücksichtigen gibt, damit beschäftigt sich dieser Tipp.

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  • Announcing Oracle Database Mobile Server 11gR2

    - by Eric Jensen
    I'm pleased to announce that Oracle Database Mobile Server 11gR2 has been released. It's available now for download by existing customers, or anyone who wants to try it out. New features include: Support for J2ME platforms, specifically CDC platforms including OJEC(this is in addition to our existing support for Java SE and SE Embedded) Per-application integration with Berkeley DB on Android Server-side support for Apache TomEE platform Adding support for Oracle Java Micro Edition Embedded Client (OJEC for short) is an important milestone for us; it enables Database Mobile Server to work with any of the incredibly wide array of devices that run J2ME. In particular, it enables management of  networks of embedded devices, AKA machine to machine (M2M) networks. As these types of networks become more common in areas like healthcare, automotive, and manufacturing, we're seeing demand for Database Mobile Server from new and different areas. This is in addition to our existing array of mobile device use cases. The Android integration feature with Berkeley DB represents the completion of phase I of our Android support plan, we now offer a full set of sync, device and app management features for that platform. Going forward, we plan to continue the dual-focus approach, supporting mobile platforms such as Android, and iOS (hint) on the one hand, and networks of embedded M2M devices on the other. In either case, Database Mobile Server continues to be the best way to connect data-driven applications to an Oracle backend.

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  • SQL Server Database Settings

    - by rbishop
    For those using Data Relationship Management on Oracle DB this does not apply, but for those using Microsoft SQL Server it is highly recommended that you run with Snapshot Isolation Mode. The Data Governance module will not function correctly without this mode enabled. All new Data Relationship Management repositories are created with this mode enabled by default. This mode makes SQL Server (2005+) behave more like Oracle DB where readers simply see older versions of rows while a write is in progress, instead of readers being blocked by locks while a write takes place. Many common sources of deadlocks are eliminated. For example, if one user starts a 5 minute transaction updating half the rows in a table, without snapshot isolation everyone else reading the table will be blocked waiting. With snapshot isolation, they will see the rows as they were before the write transaction started. Conversely, if the readers had started first, the writer won't be stuck waiting for them to finish reading... the writes can begin immediately without affecting the current transactions. To make this change, make sure no one is using the target database (eg: put it into single-user mode), then run these commands: ALTER DATABASE [DB] SET ALLOW_SNAPSHOT_ISOLATION ONALTER DATABASE [DB] SET READ_COMMITTED_SNAPSHOT ON Please make sure you coordinate with your DBA team to ensure tempdb is appropriately setup to support snapshot isolation mode, as the extra row versions are stored in tempdb until the transactions are committed. Let me take this opportunity to extremely strongly highly recommend that you use solid state storage for your databases with appropriate iSCSI, FiberChannel, or SAN bandwidth. The performance gains are significant and there is no excuse for not using 100% solid state storage in 2013. Actually unless you need to store petabytes of archival data, there is no excuse for using hard drives in any systems, whether laptops, desktops, application servers, or database servers. The productivity benefits alone are tremendous, not to mention power consumption, heat, etc.

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  • Oracle NoSQL Database: Cleaner Performance

    - by Charles Lamb
    In an earlier post I noted that Berkeley DB Java Edition cleaner performance had improved significantly in release 5.x. From an Oracle NoSQL Database point of view, this is important because Berkeley DB Java Edition is the core storage engine for Oracle NoSQL Database. Many contemporary NoSQL Databases utilize log based (i.e. append-only) storage systems and it is well-understood that these architectures also require a "cleaning" or "compaction" mechanism (effectively a garbage collector) to free up unused space. 10 years ago when we set out to write a new Berkeley DB storage architecture for the BDB Java Edition ("JE") we knew that the corresponding compaction mechanism would take years to perfect. "Cleaning", or GC, is a hard problem to solve and it has taken all of those years of experience, bug fixes, tuning exercises, user deployment, and user feedback to bring it to the mature point it is at today. Reports like Vinoth Chandar's where he observes a 20x improvement validate the maturity of JE's cleaner. Cleaner performance has a direct impact on predictability and throughput in Oracle NoSQL Database. A cleaner that is too aggressive will consume too many resources and negatively affect system throughput. A cleaner that is not aggressive enough will allow the disk storage to become inefficient over time. It has to Work well out of the box, and Needs to be configurable so that customers can tune it for their specific workloads and requirements. The JE Cleaner has been field tested in production for many years managing instances with hundreds of GBs to TBs of data. The maturity of the cleaner and the entire underlying JE storage system is one of the key advantages that Oracle NoSQL Database brings to the table -- we haven't had to reinvent the wheel.

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  • Service Catalogs for Database as a Service

    - by B R Clouse
    At the end of last month, I had the opportunity to present a speaking session at Oracle OpenWorld: Database as a Service: Creating a Database Cloud Service Catalog.  The session was well-attended which would have surprised me several months ago when I started researching this topic.  At that time, I thought of service catalogs as something trivial which could be explained in a few simple slides.  But while looking at all the different options and approaches available, I came to learn that designing a succinct and effective catalog is not a trivial task, and mistakes can lead to confusion and unintended side effects.  And when the room filled up, my new point of view was confirmed. In case you missed the session, or were able to attend but would like more details, I've posted a white paper that covers the topics from the session, and more.  We start with an overview of the components of a service catalog: And then look at several customer case studies of service catalogs for DBaaS.  Synthesizing those examples, we summarize the main options for defining the service categories and their levels.  We end with a template for defining Bronze | Silver | Gold service tiers for Oracle Database Services. The paper is now available here - watch for updates as we work to expand some sections and incorporate readers' feedback (hint - that includes your feedback). Visit our OTN page for additional Database Cloud collateral.

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  • NHibernate mapping error SQL Server 2008 Express

    - by developer
    Hi All, I tried an example from NHibernate in Action book and when I try to run the app, it throws an exception saying "Could not compile the mapping document: HelloNHibernate.Employee.hbm.xml" Below is my code, Employee.hbm.xml <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" auto-import="true"> <class name="HelloNHibernate.Employee, HelloNHibernate" lazy="false" table="Employee"> <id name="id" access="field"> <generator class="native"/> </id> <property name="name" access="field" column="name"/> <many-to-one access="field" name="manager" column="manager" cascade="all"/> </class> Program.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using NHibernate; using System.Reflection; using NHibernate.Cfg; namespace HelloNHibernate { class Program { static void Main(string[] args) { CreateEmployeeAndSaveToDatabase(); UpdateTobinAndAssignPierreHenriAsManager(); LoadEmployeesFromDatabase(); Console.WriteLine("Press any key to exit..."); Console.ReadKey(); } static void CreateEmployeeAndSaveToDatabase() { Employee tobin = new Employee(); tobin.name = "Tobin Harris"; using (ISession session = OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { session.Save(tobin); transaction.Commit(); } Console.WriteLine("Saved Tobin to the database"); } } static ISession OpenSession() { if (factory == null) { Configuration c = new Configuration(); c.AddAssembly(Assembly.GetCallingAssembly()); factory = c.BuildSessionFactory(); } return factory.OpenSession(); } static void LoadEmployeesFromDatabase() { using (ISession session = OpenSession()) { IQuery query = session.CreateQuery("from Employee as emp order by emp.name asc"); IList<Employee> foundEmployees = query.List<Employee>(); Console.WriteLine("\n{0} employees found:", foundEmployees.Count); foreach (Employee employee in foundEmployees) Console.WriteLine(employee.SayHello()); } } static void UpdateTobinAndAssignPierreHenriAsManager() { using (ISession session = OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { IQuery q = session.CreateQuery("from Employee where name='Tobin Harris'"); Employee tobin = q.List<Employee>()[0]; tobin.name = "Tobin David Harris"; Employee pierreHenri = new Employee(); pierreHenri.name = "Pierre Henri Kuate"; tobin.manager = pierreHenri; transaction.Commit(); Console.WriteLine("Updated Tobin and added Pierre Henri"); } } } static ISessionFactory factory; } } Employee.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace HelloNHibernate { class Employee { public int id; public string name; public Employee manager; public string SayHello() { return string.Format("'Hello World!', said {0}.", name); } } } App.config <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="hibernate-configuration" type="NHibernate.Cfg.ConfigurationSectionHandler,NHibernate"/> </configSections> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property> <property name="connection.connection_string"> Data Source=SQLEXPRESS2008;Integrated Security=True; User ID=SQL2008;Password=;initial catalog=HelloNHibernate </property> <property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property> <property name="show_sql">false</property> </session-factory> </hibernate-configuration> </configuration>

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  • MS Access 2003 - Unbound Form uses INSERT statement to save to table; what about subforms?

    - by Justin
    So I have an unbound form that I use to save data to a table on button click. Is there a way I can have subforms for entry that will allow me to save data to the table within that same button click? Basically I want to add more entry options for the user, and while I know other ways to do it, I am particularly curious about doing it this way (if it can be done). So lets say the 'parent form' is frmMain. And there are two child forms "sub1" and "sub2". Just for example sake lets say on frmMain there are two text boxes: txtTitle & txtAuthor. sub1 and sub2 both have a text Box on them that represent something like prices. The idea is Title & author of a book, and then a price at each store (simplified). So I tried this (because I thought it was worth a shot): Dim db as DAO.database Dim sql as String sql = "INSERT INTO (Title, Author, PriceA, PriceB) VALUES (" if not isnull(me.txtTitle) then sql = sql & """" & me.txtTitle & """," Else sql = sql & " NULL," End If if not IsNull(me.txtAuthor) then sql = sql & " """ & me.txtAuthor & """," else sql = sql & " NULL," end if if not IsNull (forms!sub1.txtPrice) then sql = sql & " """ & forms!sub1.txtPrice & """," else sql = sql & " NULL," end if without finishing the code, i think you may see the GOTCHA i am headed for. I tried this and got an "Access cannot find the form "" ". I think I can pretty much see why on this approach too, because when I click the button that calls the new sub form into the parent form, the values that were just entered are not held/saved as sub1 closes and sub2 opens. I should mention that the idea above is not intended to be a one or the other approach, rather both sub forms used everytime. so this is an example. i want to use this method (if possible) to have about 7 different sub form choices in one form, and be able to save to a table via a SQL statement. I realize that there may be better ways, but I am just wondering if I can get there with this approach out of curiousity. Thanks as always!

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  • Why does WebSharingAppDemo-CEProviderEndToEnd sample still need a client db connection after scope c

    - by Don
    I'm researching a way to build an n-tierd sync solution. From the WebSharingAppDemo-CEProviderEndToEnd sample it seems almost feasable however for some reason, the app will only sync if the client has a live SQL db connection. Can some one explain what I'm missing and how to sync without exposing SQL to the internet? The problem I'm experiencing is that when I provide a Relational sync provider that has an open SQL connection from the client, then it works fine but when I provide a Relational sync provider that has a closed but configured connection string, as in the example, I get an error from the WCF stating that the server did not receive the batch file. So what am I doing wrong? SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder(); builder.DataSource = hostName; builder.IntegratedSecurity = true; builder.InitialCatalog = "mydbname"; builder.ConnectTimeout = 1; provider.Connection = new SqlConnection(builder.ToString()); // provider.Connection.Open(); **** un-commenting this causes the code to work** //create anew scope description and add the appropriate tables to this scope DbSyncScopeDescription scopeDesc = new DbSyncScopeDescription(SyncUtils.ScopeName); //class to be used to provision the scope defined above SqlSyncScopeProvisioning serverConfig = new SqlSyncScopeProvisioning(); .... The error I get occurs in this part of the WCF code: public SyncSessionStatistics ApplyChanges(ConflictResolutionPolicy resolutionPolicy, ChangeBatch sourceChanges, object changeData) { Log("ProcessChangeBatch: {0}", this.peerProvider.Connection.ConnectionString); DbSyncContext dataRetriever = changeData as DbSyncContext; if (dataRetriever != null && dataRetriever.IsDataBatched) { string remotePeerId = dataRetriever.MadeWithKnowledge.ReplicaId.ToString(); //Data is batched. The client should have uploaded this file to us prior to calling ApplyChanges. //So look for it. //The Id would be the DbSyncContext.BatchFileName which is just the batch file name without the complete path string localBatchFileName = null; if (!this.batchIdToFileMapper.TryGetValue(dataRetriever.BatchFileName, out localBatchFileName)) { //Service has not received this file. Throw exception throw new FaultException<WebSyncFaultException>(new WebSyncFaultException("No batch file uploaded for id " + dataRetriever.BatchFileName, null)); } dataRetriever.BatchFileName = localBatchFileName; } Any ideas?

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  • Cardinality Estimation Bug with Lookups in SQL Server 2008 onward

    - by Paul White
    Cost-based optimization stands or falls on the quality of cardinality estimates (expected row counts).  If the optimizer has incorrect information to start with, it is quite unlikely to produce good quality execution plans except by chance.  There are many ways we can provide good starting information to the optimizer, and even more ways for cardinality estimation to go wrong.  Good database people know this, and work hard to write optimizer-friendly queries with a schema and metadata (e.g. statistics) that reduce the chances of poor cardinality estimation producing a sub-optimal plan.  Today, I am going to look at a case where poor cardinality estimation is Microsoft’s fault, and not yours. SQL Server 2005 SELECT th.ProductID, th.TransactionID, th.TransactionDate FROM Production.TransactionHistory AS th WHERE th.ProductID = 1 AND th.TransactionDate BETWEEN '20030901' AND '20031231'; The query plan on SQL Server 2005 is as follows (if you are using a more recent version of AdventureWorks, you will need to change the year on the date range from 2003 to 2007): There is an Index Seek on ProductID = 1, followed by a Key Lookup to find the Transaction Date for each row, and finally a Filter to restrict the results to only those rows where Transaction Date falls in the range specified.  The cardinality estimate of 45 rows at the Index Seek is exactly correct.  The table is not very large, there are up-to-date statistics associated with the index, so this is as expected. The estimate for the Key Lookup is also exactly right.  Each lookup into the Clustered Index to find the Transaction Date is guaranteed to return exactly one row.  The plan shows that the Key Lookup is expected to be executed 45 times.  The estimate for the Inner Join output is also correct – 45 rows from the seek joining to one row each time, gives 45 rows as output. The Filter estimate is also very good: the optimizer estimates 16.9951 rows will match the specified range of transaction dates.  Eleven rows are produced by this query, but that small difference is quite normal and certainly nothing to worry about here.  All good so far. SQL Server 2008 onward The same query executed against an identical copy of AdventureWorks on SQL Server 2008 produces a different execution plan: The optimizer has pushed the Filter conditions seen in the 2005 plan down to the Key Lookup.  This is a good optimization – it makes sense to filter rows out as early as possible.  Unfortunately, it has made a bit of a mess of the cardinality estimates. The post-Filter estimate of 16.9951 rows seen in the 2005 plan has moved with the predicate on Transaction Date.  Instead of estimating one row, the plan now suggests that 16.9951 rows will be produced by each clustered index lookup – clearly not right!  This misinformation also confuses SQL Sentry Plan Explorer: Plan Explorer shows 765 rows expected from the Key Lookup (it multiplies a rounded estimate of 17 rows by 45 expected executions to give 765 rows total). Workarounds One workaround is to provide a covering non-clustered index (avoiding the lookup avoids the problem of course): CREATE INDEX nc1 ON Production.TransactionHistory (ProductID) INCLUDE (TransactionDate); With the Transaction Date filter applied as a residual predicate in the same operator as the seek, the estimate is again as expected: We could also force the use of the ultimate covering index (the clustered one): SELECT th.ProductID, th.TransactionID, th.TransactionDate FROM Production.TransactionHistory AS th WITH (INDEX(1)) WHERE th.ProductID = 1 AND th.TransactionDate BETWEEN '20030901' AND '20031231'; Summary Providing a covering non-clustered index for all possible queries is not always practical, and scanning the clustered index will rarely be optimal.  Nevertheless, these are the best workarounds we have today. In the meantime, watch out for poor cardinality estimates when a predicate is applied as part of a lookup. The worst thing is that the estimate after the lookup join in the 2008+ plans is wrong.  It’s not hopelessly wrong in this particular case (45 versus 16.9951 is not the end of the world) but it easily can be much worse, and there’s not much you can do about it.  Any decisions made by the optimizer after such a lookup could be based on very wrong information – which can only be bad news. If you think this situation should be improved, please vote for this Connect item. © 2012 Paul White – All Rights Reserved twitter: @SQL_Kiwi email: [email protected]

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  • SQL Azure: Notes on Building a Shard Technology

    - by Herve Roggero
    In Chapter 10 of the book on SQL Azure (http://www.apress.com/book/view/9781430229612) I am co-authoring, I am digging deeper in what it takes to write a Shard. It's actually a pretty cool exercise, and I wanted to share some thoughts on how I am designing the technology. A Shard is a technology that spreads the load of database requests over multiple databases, as transparently as possible. The type of shard I am building is called a Vertical Partition Shard  (VPS). A VPS is a mechanism by which the data is stored in one or more databases behind the scenes, but your code has no idea at design time which data is in which database. It's like having a mini cloud for records instead of services. Imagine you have three SQL Azure databases that have the same schema (DB1, DB2 and DB3), you would like to issue a SELECT * FROM Users on all three databases, concatenate the results into a single resultset, and order by last name. Imagine you want to ensure your code doesn't need to change if you add a new database to the shard (DB4). Now imagine that you want to make sure all three databases are queried at the same time, in a multi-threaded manner so your code doesn't have to wait for three database calls sequentially. Then, imagine you would like to obtain a breadcrumb (in the form of a new, virtual column) that gives you a hint as to which database a record came from, so that you could update it if needed. Now imagine all that is done through the standard SqlClient library... and you have the Shard I am currently building. Here are some lessons learned and techniques I am using with this shard: Parellel Processing: Querying databases in parallel is not too hard using the Task Parallel Library; all you need is to lock your resources when needed Deleting/Updating Data: That's not too bad either as long as you have a breadcrumb. However it becomes more difficult if you need to update a single record and you don't know in which database it is. Inserting Data: I am using a round-robin approach in which each new insert request is directed to the next database in the shard. Not sure how to deal with Bulk Loads just yet... Shard Databases:  I use a static collection of SqlConnection objects which needs to be loaded once; from there on all the Shard commands use this collection Extension Methods: In order to make it look like the Shard commands are part of the SqlClient class I use extension methods. For example I added ExecuteShardQuery and ExecuteShardNonQuery methods to SqlClient. Exceptions: Capturing exceptions in a multi-threaded code is interesting... but I kept it simple for now. I am using the ConcurrentQueue to store my exceptions. Database GUID: Every database in the shard is given a GUID, which is calculated based on the connection string's values. DataTable. The Shard methods return a DataTable object which can be bound to objects.  I will be sharing the code soon as an open-source project in CodePlex. Please stay tuned on twitter to know when it will be available (@hroggero). Or check www.bluesyntax.net for updates on the shard. Thanks!

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  • Connecting to SQL Server in Php - Extension Err

    - by John Doe
    <html> <head> <title>Connecting </title> </head> <body> <?php $host = "*.*.*.*"; $username = "xxx"; $password = "xxx"; $db_name = "xxx"; $db = mssql_connect($host, $username,$password) or die("Couldnt Connect"); $selected = mssql_select_db($db_name, $db) or die("Couldnt open database"); ?> </body> </html> My error message is: Fatal error: Call to undefined function mssql_connect() in C:\wamp\www\php\dbase.php on line 12 I am using WampServer 2.0 on Php 5.3.0 When I check the extensions, php_mssql is Checked. I also checked the php.ini file to make sure it is not commented out. I have my file dbase.php saved in C:\wamp\www\php. I have tried stopping the service, closing everything, and running it again. I know the problem is that the extension file is not being included somehow. The below is copied from my php.ini file. Note I made all http = /http to avoid posting Links. ;;;;;;;;;;;;;;;;;;;;;;;;; ; Paths and Directories ; ;;;;;;;;;;;;;;;;;;;;;;;;; ; UNIX: "/path1:/path2" ;include_path = ".:/php/includes" ; Windows: "\path1;\path2" include_path = "C:\wamp\bin\php\php5.3.0\ext" ; ; PHP's default setting for include_path is ".;/path/to/php/pear" ; /http://php.net/include-path ; The root of the PHP pages, used only if nonempty. ; if PHP was not compiled with FORCE_REDIRECT, you SHOULD set doc_root ; if you are running php as a CGI under any web server (other than IIS) ; see documentation for security issues. The alternate is to use the ; cgi.force_redirect configuration below ; /http://php.net/doc-root doc_root = ; The directory under which PHP opens the script using /~username used only ; if nonempty. ; /http://php.net/user-dir user_dir = ; Directory in which the loadable extensions (modules) reside. ; /http://php.net/extension-dir ; extension_dir = "./" ; On windows: ; extension_dir = "ext" extension_dir = "c:/wamp/bin/php/php5.3.0/ext/" ; Whether or not to enable the dl() function. The dl() function does NOT work ; properly in multithreaded servers, such as IIS or Zeus, and is automatically ; disabled on them. ; /http://php.net/enable-dl enable_dl = Off ; cgi.force_redirect is necessary to provide security running PHP as a CGI under ; most web servers. Left undefined, PHP turns this on by default. You can ; turn it off here AT YOUR OWN RISK ; You CAN safely turn this off for IIS, in fact, you MUST. ; /http://php.net/cgi.force-redirect ;cgi.force_redirect = 1 ; if cgi.nph is enabled it will force cgi to always sent Status: 200 with ; every request. PHP's default behavior is to disable this feature. ;cgi.nph = 1 ; if cgi.force_redirect is turned on, and you are not running under Apache or Netscape ; (iPlanet) web servers, you MAY need to set an environment variable name that PHP ; will look for to know it is OK to continue execution. Setting this variable MAY ; cause security issues, KNOW WHAT YOU ARE DOING FIRST. ; /http://php.net/cgi.redirect-status-env ;cgi.redirect_status_env = ; ; cgi.fix_pathinfo provides real PATH_INFO/PATH_TRANSLATED support for CGI. PHP's ; previous behaviour was to set PATH_TRANSLATED to SCRIPT_FILENAME, and to not grok ; what PATH_INFO is. For more information on PATH_INFO, see the cgi specs. Setting ; this to 1 will cause PHP CGI to fix its paths to conform to the spec. A setting ; of zero causes PHP to behave as before. Default is 1. You should fix your scripts ; to use SCRIPT_FILENAME rather than PATH_TRANSLATED. ; /http://php.net/cgi.fix-pathinfo ;cgi.fix_pathinfo=1 ; FastCGI under IIS (on WINNT based OS) supports the ability to impersonate ; security tokens of the calling client. This allows IIS to define the ; security context that the request runs under. mod_fastcgi under Apache ; does not currently support this feature (03/17/2002) ; Set to 1 if running under IIS. Default is zero. ; /http://php.net/fastcgi.impersonate ;fastcgi.impersonate = 1; ; Disable logging through FastCGI connection. PHP's default behavior is to enable ; this feature. ;fastcgi.logging = 0 ; cgi.rfc2616_headers configuration option tells PHP what type of headers to ; use when sending HTTP response code. If it's set 0 PHP sends Status: header that ; is supported by Apache. When this option is set to 1 PHP will send ; RFC2616 compliant header. ; Default is zero. ; /http://php.net/cgi.rfc2616-headers ;cgi.rfc2616_headers = 0 ;;;;;;;;;;;;;;;; ; File Uploads ; ;;;;;;;;;;;;;;;; ; Whether to allow HTTP file uploads. ; /http://php.net/file-uploads file_uploads = On ; Temporary directory for HTTP uploaded files (will use system default if not ; specified). ; /http://php.net/upload-tmp-dir upload_tmp_dir = "c:/wamp/tmp" ; Maximum allowed size for uploaded files. ; /http://php.net/upload-max-filesize upload_max_filesize = 2M Also, my php.ini file is saved in: C:\wamp\bin\apache\Apache2.2.11\bin

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  • Trying to add data to sql from link click and return results via jquery or ajax

    - by Jay Schires
    I am not familiar with jquery or ajax, but i do know it is whats needed to perform the action I want. I have created a wordpress plugin that updates a database table based on the users click. Right now it refreshes the page to return the results, but I want to stop the page refresh and return data via ajax I believe. If anyone is interested in helping me figure this out I would be very appreciative or even willing to pay. Thanks! Here is the plugin code: function BoardLikeItGetDelim($postid) { global $wp_rewrite; if($wp_rewrite->using_permalinks()) { if(isset($_GET['mbpost'])) return "?mbpost=".$postid."&"; return "?"; } else { if(isset($_GET['mbpost'])) return "&mbpost=".$postid."&"; return "&"; } } function AddBoardLikeItButton($postid) { global $user_ID; if(isset($_GET['board-like-it-action']) && $_GET['board-like-it-action'] == "like" && $_GET['bpid'] == $postid) BoardLikeItLike($user_ID, $_GET['bpid']); if(isset($_GET['board-like-it-action']) && $_GET['board-like-it-action'] == "unlike" && $_GET['bpid'] == $postid) BoardLikeItUnLike($user_ID, $_GET['bpid']); $num_likes = BoardLikeItGetNumLikes($postid); if(!BoardLikeItIsLiked($user_ID, $postid)) echo "<HREF LINK='".BoardLikeItGetDelim($postid)."board-like-it-action=like&bpid=".$postid."#mngl-board-post-message-".$postid."'>Like</a> ".$num_likes."" . "<br/>"; else echo "<HREF LINK ='".BoardLikeItGetDelim($postid)."board-like-it-action=unlike&bpid=".$postid."#mngl-board-post-message-".$postid."'>Un-Like</a> " . "<br/><span style='display: inline-block; padding: 0px; bottom: -5px; position: relative; border: 0px;'><IMAGE='". get_bloginfo('wpurl')."/wp-content/plugins/board-like-it/top-up.png' /></span><div style='-moz-border-radius: 4px; -khtml-border-radius: 4px; -webkit-border-radius: 4px; font-family: Verdana, Geneva, sans-serif; font-size: 10px; color: #000; background-color: #B8C9DB; width: 90%; margin: 0px; display: block; padding-top: 4px; padding-right: 5px; padding-bottom: 4px; padding-left: 6px;'>" . "<IMAGE='". get_bloginfo('wpurl')."/wp-content/plugins/board-like-it/thumb_up.png'/> " .BoardLikeItShowLikers($postid). "like this." . "</div>"; } function BoardLikeItShowLikers($postid) { global $wpdb; $result = $wpdb->get_var($wpdb->prepare("SELECT `likers` FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); $results = explode(',', $result); $names = ""; if($results[0] != "") foreach($results as $r) { $userinfo = get_usermeta($r, 'user_login'); $names .= $userinfo.", "; } return $names; } function BoardLikeItGetNumLikes($postid) { global $wpdb; $result = $wpdb->get_var($wpdb->prepare("SELECT `likers` FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); $results = explode(',', $result); if($results[0] != '') return count($results)."<br/><span style='display: inline-block; padding: 0px; bottom: -5px; position: relative; border: 0px;'><IMAGE='". get_bloginfo('wpurl')."/wp-content/plugins/board-like-it/top-up.png' /></span><div style='-moz-border-radius: 4px; -khtml-border-radius: 4px; -webkit-border-radius: 4px; font-family: Verdana, Geneva, sans-serif; font-size: 10px; color: #000; background-color: #B8C9DB; width: 90%; margin: 0px; display: inline-block; border: 0px; padding-top: 0px; padding-right: 5px; padding-bottom: 1px; padding-left: 6px;'>" . "<IMAGE='". get_bloginfo('wpurl')."/wp-content/plugins/board-like-it/thumb_up.png'/> " .BoardLikeItShowLikers($postid). "likes this." . "</div>"; else return ""; } function BoardLikeItLike($user_ID, $postid) { global $wpdb; $likers = array(); $likersnew = array(); $result = $wpdb->get_var($wpdb->prepare("SELECT `likers` FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); $results = explode(',',$result); if($results[0] != "") { if(!in_array($user_ID, $results)) $results[] = $user_ID; $likers = implode(',',$results); $wpdb->query($wpdb->prepare("UPDATE ".BoardLikeItGetDBName()." SET `likers` = '{$likers}' WHERE `mngl_id` = {$postid}")); } else { $likersnew[] = $user_ID; $likersnew = implode(',',$likersnew); $wpdb->query($wpdb->prepare("INSERT INTO ".BoardLikeItGetDBName()." (`mngl_id`, `likers`) VALUES ('{$postid}', '{$likersnew}')")); } } function BoardLikeItUnLike($user_ID, $postid) { global $wpdb; $likers = array(); $result = $wpdb->get_var($wpdb->prepare("SELECT `likers` FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); $results = explode(',', $result); if(in_array($user_ID, $results)) { $results = BoardLikeItRemoveFromArray($results, $user_ID); if(!empty($results)) { $likers = implode(',', $results); $wpdb->query($wpdb->prepare("UPDATE ".BoardLikeItGetDBName()." SET `likers` = '{$likers}' WHERE `mngl_id` = {$postid}")); } else { $wpdb->query($wpdb->prepare("DELETE FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); } } } function BoardLikeItIsLiked($user_ID, $postid) { global $wpdb; $result = $wpdb->get_var($wpdb->prepare("SELECT `likers` FROM ".BoardLikeItGetDBName()." WHERE `mngl_id` = {$postid}")); $results = explode(',', $result); if(in_array($user_ID, $results)) return true; else return false; } function BoardLikeItActivate() { global $wpdb; $charset_collate = ''; if($wpdb->has_cap('collation')) { if(!empty($wpdb->charset)) $charset_collate = "DEFAULT CHARACTER SET $wpdb->charset"; if(!empty($wpdb->collate)) $charset_collate .= " COLLATE $wpdb->collate"; } $table_sql = "CREATE TABLE ".BoardLikeItGetDBName()."( `mngl_id` int(11) NOT NULL, `likers` longtext NOT NULL, PRIMARY KEY (`mngl_id`)) {$charset_collate};"; require_once(ABSPATH.'wp-admin/includes/upgrade.php'); dbDelta($table_sql); } function BoardLikeItGetDBName() { global $wpdb; return $wpdb->prefix."board_like_it"; } function BoardLikeItRemoveFromArray($arr, $key) { $new = array(); foreach($arr as $j => $i) { if($i != $key) $new[] = $i; } return $new; }

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  • How do I encapsulate the application server from the web and database servers?

    - by SNyamathi
    So I've been doing some reading and it seems like the best practice would be to have separate database, application, and web servers. There are a few things that I've failed to understand - please feel free to recommend any reading materials that would address these topics. Database (assume MySQL) Application server communication: Does the database server do any sort of checks on the SQL commands sent / returned, or is it just a "dumb pipe" that responds to SQL commands by spitting back data? Application server (assume Tomcat) Web Server Almost the reverse here, is it the web server that is more of a pipe to the internet that forwards requests to the application server and spits back responses? I'm not wording this well, but I'm trying to ask - is it the application server that is responsible for validating data received by from requests? ex: Parsing POSTs Validating user logins Encrypting decrypting data Furthermore, how do these two servers communicate? I'm trying to keep things as flexible as possible here, so while I could write a web server in Java and use Java to communicate between the web and app server, that doesn't sound very modular. What if I want to use Python or some other language to replace the web server later on? What if I want to make a non-web facing application used in house written in C++ or something.

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  • What is the typical maximum number of database connections for Oracle running on Windows server ?

    - by Sake
    We are maintaining a database server that serve a large number of clients. Each client typically running serveral client-applications. The total number of connections to the database server (Oracle 9i) is reaching 800 connections on peak load. The windows 2003 server is starting to run out of memory. We are now planning to move to 64bit Windows in order to gain higher memory capability. As a developer I suggest moving to multi-tier architecture with conneciton pooling, which I believe is a natural solution to this problem. However, in order to support my idea, I want the information on: what exactly is the typical number of connections allowed for Oracle database ? What is the problem when the number connections is too high ? Too much memory comsumption ? or too many sockets opened ? or too many context switching between threads ? To be a little bit specific, how could Oracle Forms application scale to thousand of users without facing this problem ? Shall Oracle RAC applied to this case ? I'm sure the answer to this question should depend on quite a number of factors, like the exact spec of the hardware being used. I'm expecting a rough estimation or some experience from the real world.

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  • iPhone Audio Queue Service sample units

    - by pion
    I am looking at Audio Queue Services document specifically on the following code: // Writing an audio queue buffer to disk AudioFileWritePackets ( // 1 pAqData->mAudioFile, // 2 false, // 3 inBuffer->mAudioDataByteSize, // 4 inPacketDesc, // 5 pAqData->mCurrentPacket, // 6 &inNumPackets, // 7 inBuffer->mAudioData // 8 ); inBuffer-mAudioDataByteSize is the number of bytes of audio data being written. inBuffer-mAudioData is the new audio data to write to the audio file. Assuming the sample rate is 44100. AudioStreamBasicDescription mDataFormat; mDataFormat.mSampleRate = 44100.0f; mDataFormat.mBitsPerChannel = 16; ... NSInteger numberSamples = inBuffer->mAudioDataByteSize / 2; SInt16 *audioSample = (SInt16 *)inBuffer->mAudioData; I use core-plot to plot the above where x axis is number of sample [1 .. numberSamples] and the y axis is audioSample[0] .. audioSample[numberSamples]. I can see the chart in "real-time" where the y axis goes up and down depending the loudness of my voice. Beginner questions: What does the audioSample represent? What am I looking at here? What is the unit of audioSample? What do I need to do if I just want to plot the range between 50 - 100 Hz? Thanks in advance for your help.

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  • Scaling gwt's "Contacts" (sample project) AppController with MVP

    - by brad
    I'm just learning GWT so I'm still trying to sort out all of its quirks and features. I'm reading through the example they give illustrating the MVP pattern, and I pretty much get it, except I'm wondering about one thing. The AppController they use implements the ValueChangeHandler interface and the onValueChange method is triggered when history changes. My problem is with this onValueChange in the AppController (i've included it below for anyone who hasn't seen the sample project). It's doing a string comparison on the history token sent in and instantiating the appropriate presenter to handle the action. This is all fine and dandy for the sample app with 3 actions, but how would one scale this to a real app with many more actions? Sticking to this pattern would lead to a pretty large/ugly else if, but I'm still too new to GWT (and java) to infer a better pattern for larger apps. Any help is greatly appreciated! public class AppController implements Presenter, ValueChangeHandler<String> { ... public void onValueChange(ValueChangeEvent<String> event) { String token = event.getValue(); if (token != null) { Presenter presenter = null; if (token.equals("list")) { presenter = new ContactsPresenter(rpcService, eventBus, new ContactsView()); } else if (token.equals("add")) { presenter = new EditContactPresenter(rpcService, eventBus, new EditContactView()); } else if (token.equals("edit")) { presenter = new EditContactPresenter(rpcService, eventBus, new EditContactView()); } if (presenter != null) { presenter.go(container); } } } }

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  • Webservices on iPhone - wsdl2objc - Sample Code?

    - by markmcgookin
    I have recently downloaded the most recent build of this awesome tool WSDL2OBJC from google code here: http://code.google.com/p/wsdl2objc/ After a bit of tweaking and downloading the latest version of the trunk from the svn repo I got a version that created the code for a WSDL I am using and compiles great and actually installs on my phone! However, I'm not doing anything with it yet, because I am not really sure how to. There is very little in the way of sample code on the site, and there is a sample file in the project if you download it, but again it is very complicated and there are no real bits of documentation. Has anyone managed to successfully use this stuff? It seems SOOO powerful and useful but from a look around the Internet, no one knows how to use it. We (all) would love someone who has figured it out to post a simple project or detailed walk-through of implementing this so we can put the code that lots of people have worked hard on to good use. If anyone has found a blog entry or has this information it would be great to see! I am totally stuck... with no errors. I would love to know how to use this now that it's all compiled successfully!

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  • Apple's Sample App TopSongs has 26 Leaks, Ugh!

    - by RoLYroLLs
    Hey all, I've been building an app for a client and part of it uses Apple's TopSongs sample app to download data on another thread. I finally got enough done to start testing that part and found 1000 leaks!!! A closer look at the leaks made me check TopSongs for leaks, since none of the my methods were in leaks report. Running TopSongs returned 26 leaks. Not quite sure how to fix them, or if they are part of some library from Apple. I bet you're asking if it has 26, why do you have 1000? Well, I use their sample to make roughly 48 calls to webservices to get all the information needed on initial install (48 calls x 26 leaks = 1248 leaks!!). Later it makes at least 12 calls + 4 to check for updated information on other sections of the app. Can't do a thing about it, can't make one call, or less calls, please don't comment about this part. I seen people respond to posts that aren't necessarily answering the question the user originally posted, which in this case is has anyone tried patching up the leaks, if they are patchable, or is this a bug in Apple's libraries? Thanks so much.

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  • Unit Testing - Algorithm or Sample based ?

    - by ohadsc
    Say I'm trying to test a simple Set class public IntSet : IEnumerable<int> { Add(int i) {...} //IEnumerable implementation... } And suppose I'm trying to test that no duplicate values can exist in the set. My first option is to insert some sample data into the set, and test for duplicates using my knowledge of the data I used, for example: //OPTION 1 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //3 will be added 3 times var values = new List<int> {1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I know 3 is the only candidate to appear multiple times int counter = 0; foreach (int i in set) if (i == 3) counter++; Assert.AreEqual(1, counter); } My second option is to test for my condition generically: //OPTION 2 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //The following could even be a list of random numbers with a duplicate var values = new List<int> { 1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I am not using my prior knowledge of the sample data //the following line would work for any data CollectionAssert.AreEquivalent(new HashSet<int>(values), set); } Of course, in this example, I conveniently have a set implementation to check against, as well as code to compare collections (CollectionAssert). But what if I didn't have either ? This is the situation when you are testing your real life custom business logic. Granted, testing for expected conditions generically covers more cases - but it becomes very similar to implementing the logic again (which is both tedious and useless - you can't use the same code to check itself!). Basically I'm asking whether my tests should look like "insert 1, 2, 3 then check something about 3" or "insert 1, 2, 3 and check for something in general" EDIT - To help me understand, please state in your answer if you prefer OPTION 1 or OPTION 2 (or neither, or that it depends on the case, etc )

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