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• Adding linked table to Access 2003 while keeping ODBC connection info in MDB

  - by webworm

  I have an Access 2003 database MDB where all of the tables exist as linked tables within SQL Server 2005. The MDB file contains all of the ODBC information that points to the correct SQL Server and log-on credentials (trusted connection). What I would like to do is add a new linked table to the MDB file however I am not sure how to go about specifying the ODBC connection information. When I try to add a new linked table I keep getting prompted to locate or create a DSN file. I don't want to have to create a new DSN entry on every machine, rather I would like all that information stored within the Access MDB file itself. In the existing database I can "hover" over the table names and see the ODBC connection info as a tool-tip. All I need to do is add another linked table using the same connection information. I do have access to the SQL Server where the tables are linked to,. I have already created the new table I wanted to add. I just need to find a way to link to it.

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• NHibernate not dropping foreign key constraints.

  - by Kendrick

  I'm new to NHibernate, so this is probably my mistake, but when I use: schema.Create(true, true); I get: SchemaExport [(null)]- There is already an object named 'XXX' in the database. System.Data.SqlClient.SqlException: There is already an object named 'XXX' in the database. I grabbed the SQL code nHibernate was using, ran it directly from MSSMS, and recieved similar errors. Looking into it, the generated code is not properly dropping the foreign key constraints. The drop looks like this: if exists (select 1 from sysobjects where id = OBJECT_ID(N'dbo[FK22212EAFBFE4C58]') AND parent_obj = OBJECT_ID('YYY')) alter table dbo.YYY drop constraint FK22212EAFBFE4C58 Doing a "select OBJECT_ID(N'dbo[FK22212EAFBFE4C58]')" I get null. If I take out the "dbo" (i.e. "select OBJECT_ID(N'[FK22212EAFBFE4C58]')") then the ID is returned. So, my question is, why is nHibernate adding the dbo, and why does that prevent the object from being returned (since the table owning the constraint is dbo.XXX) One of my mapping files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping namespace="CanineApp.Model" assembly="CanineApp.Model" xmlns="urn:nhibernate-mapping-2.2"> <class name="MedicalLog" table="MedicalLog" schema="dbo"> <id name="MedicalLogID" type="Int64"> <generator class="identity" /> </id> <property name="InvoiceAmount" type="Decimal" not-null="true" /> ... <many-to-one name="Canine" class="Canine" column="CanineID" not-null="true" fetch="join" /> <many-to-one name="TreatmentCategory" class="TreatmentCategory" column="TreatmentCategoryID" not-null="true" access="field.camelcase-underscore" /> </class> </hibernate-mapping>

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• EF4 querying through the generations

  - by Hans Kesting

  I have a model withs Parents, Children and Grandchildren, in a many-to-many relationship. Using this article I created POCO classes that work fine, except for one thing I can't yet figure out. When I query the Parents or Children directly using LINQ, the SQL reflects the LINQ query (a .Count() executes a COUNT in the database and so on) - fine. The Parent class has a Children property, to access it's children. But (and now for the problem) this doesn't expose an IQueryable interface but an ICollection. So when I access the Children property on a particular parent all the Parent's Children are read. Even worse, when I access the Grandchildren (theParent.Children.SelectMany(child => child.GrandChildren).Count()) then for each and every child a separate request is issued to select it's grandchildren. Changing the type of the Children property from ICollection to IQueryable doesn't solve this. Apart from missing needed methods like Add() and Remove(), EF just doesn't recognize the property then. Are there correct ways (as in: low database interaction) of querying through children (and what are they)? Or is this just not possible?

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• After a few same hql query the application freezes

  - by Oktay

  I am calling below function with the same batchNumber and it is working without problem 15 times and takes the records fromm database without problem but at 16. time the application freezes when the query.list() row is called. It just loses debug focus and not give any exception. This problem probably is not about the hql because I've seen this problem before and I used criteria instead of hql and I got pass this problem. But for this when I use "group by" in criteria(setrojection....) it doesn't return the result as hibernate model(object) just returns a list. But I need the results as model. Note: about 15 times it is just for test. This is a web aplication and user may click the button many times that calls this funtion to see the taken records from database. public List<SiteAddressModel> getSitesByBatch(String batchNumber) { try{ List<SiteAddressModel> siteList; MigrationPlanDao migrationPlanDao = ServiceFactory.getO2SiteService().getMigrationPlanDao(); Query query = this.getSession().createQuery("from " + persistentClass.getName() + " where " + "siteType =:" + "type and siteName in " + "(select distinct exchange from " + migrationPlanDao.getPersistentClass().getName() + " where migrationBatchNumber =:" + "batchNumber" + ")" ); query.setString("batchNumber", batchNumber); query.setString("type", "LLU/ASN"); System.out.println("before query"); siteList = query.list(); System.out.println("after query"); return siteList; }catch (Exception e) { e.printStackTrace(); } Hibernate version 3.2.0.ga

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• [SOLVED]Django - Passing variables to template based on db

  - by George 'Griffin

  I am trying to add a feature to my app that would allow me to enable/disable the "Call Me" button based on whether or not I am at [home|the office]. I created a model in the database called setting, it looks like this: class setting(models.Model): key = models.CharField(max_length=200) value = models.CharField(max_length=200) Pretty simple. There is currently one row, available, the value of it is the string True. I want to be able to transparently pass variables to the templates like this: {% if available %} <!-- Display button --> {% else %} <!-- Display grayed out button --> {% endif %} Now, I could add logic to every view that would check the database, and pass the variable to the template, but I am trying to stay DRY. What is the best way to do this? UPDATE I created a context processor, and added it's path to the TEMPLATE_CONTEXT_PROCESSORS, but it is not being passed to the template def available(request): available = Setting.objects.get(key="available") if open.value == "True": return {"available":True} else: return {} UPDATE TWO If you are using the shortcut render_to_response, you need to pass an instance of RequestContext to the function. from the django documentation: If you're using Django's render_to_response() shortcut to populate a template with the contents of a dictionary, your template will be passed a Context instance by default (not a RequestContext). To use a RequestContext in your template rendering, pass an optional third argument to render_to_response(): a RequestContext instance. Your code might look like this: def some_view(request): # ... return render_to_response('my_template.html', my_data_dictionary, context_instance=RequestContext(request)) Many thanks for all the help!

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• In sync query calls, one query causing other query to run slower. Why?

  - by Irchi

  Sorry for the long question, but I think this is an interesting situation and I couldn't find any explanations for it: I was involved in optimization of an application that performed a large number of sequential SELECT and INSERT statements on a single dedicated SQL Server database. The process needs to INSERT a large number of records into a table, but for each of them there should be some value mappings, which performed using SELECT statements on another table in the same database. For a specific execution, it took 90 minutes to run. I used a profiler (JProfiler - the application is Java-based) to determine how much time does each part of the application take. It yields that 60% of the time was spent on INSERT method calls, and almost 20% on SELECT calls (the rest distributed in other parts). After some trials, I came to this situation: I commented out the INSERT query that took 60% of the time. I was expecting for the total run time to be around 35 minutes, as I have removed 60% of the 90 minutes. But the whole process took the same 90 minutes (doing only SELECTs and nothing else), but each SELECT took longer this time! Everything was running sync, there were no async calls. And there was only one single thread of execution. SELECT and INSERT queries are very simple, and don't have anything special, and they are on different tables, but on the same DB. I tested with both the DB on the application machine, and on a remote network machine. I can't think of any explanation for this, as the Profiler (Application profiler, not SQL Profiler) reported the changes in the method call times, and by removing INSERT statements SELECT statements took longer to run. Can anyone give me some kind of explanation of what could have happened? (there can't be cache / query optimization stuff, because the queries were run in sync, and in a single thread, and it was far from affecting the cache this much) I should note that the bottleneck of the speed was in SQL server, using most of the CPU time.

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• Extending the CI_DB_active_record class in codeigniter 2.0

  - by ctrane

  I am writing my first program with Codeigniter, and have run into a problem. I will start with a focused description of the problem and can broaden it if I need to: I need to write a multi-dimensional array to the DB and want to use the insert_batch function from the CI_DB_active_record class to do so. The problem is that I need to write empty values as NULL for some fields while other fields need to be empty strings. The current function wraps all values with single quotes, and I cannot find a way to write null values to the database for specified fields. I would also like to increase the number of records per batch. I see how to extend models, libraries, etc., but is there a way to extend the CI_DB_active_record class without modifying core classes? The minimal amount of core class modification to make this work that I have found is modifying the following lines in the DB.php file (changing the require_once file to the new file that extends the CI_DB_active_record class and changing the CI_DB_active_record class name to the new class name): require_once(BASEPATH.'database/DB_active_rec'.EXT); if ( ! class_exists('CI_DB')) { eval('class CI_DB extends CI_DB_active_record { }'); } Can I do better?

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• PHP login, getting wrong count value from query / fetch array

  - by Chris

  Hello, *EDIT*Thanks to the comments below it has been figured out that the problem lies with the md5, without everything works as it should. But how do i implent the md5 then? I am having some troubles with the following code below to login. The database and register system are already working. The problem lies that it does not find any result at all in the query. IF the count is 0 it should redirect the user to a secured page. But this only works if i write count = 0, but this should be 0 , only if the user name and password is found he should be directed to the secure (startpage) of the site after login. For example root (username) root (password) already exists but i cannot seem to properly login with it. <?php session_start(); if (!empty($_POST["send"])) { $username = ($_POST["username"]); $password = (md5($_POST["password"])); $count = 0; $con = mysql_connect("localhost" , "root", ""); mysql_select_db("testdb", $con); $result = mysql_query("SELECT name, password FROM user WHERE name = '".$username."' AND password = '".$password."' ") or die("Error select statement"); $count = mysql_num_rows($result); if($count > 0) // always goes the to else, only works with >=0 but then the data is not found in the database, hence incorrect { $row = mysql_fetch_array($result); $_SESSION["username"] = $row["name"]; header("Location: StartPage.php"); } else { echo "Wrong login data, please try again"; } mysql_close($con); } ?>

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• Codeigniter xss_clean dilemma

  - by Henson

  I know this question has been asked over and over again, but I still haven't found the perfect answer for my liking, so here it goes again... I've been reading lots and lots polarizing comments about CI's xss_filter. Basically majority says that it's bad. Can someone elaborate how it's bad, or at least give 1 most probable scenario where it can be exploited? I've looked at the security class in CI 2.1 and I think it's pretty good as it doesn't allow malicious strings like document.cookie, document.write, etc. If the site has basically non-html presentation, is it safe to use global xss_filter (or if it's REALLY affecting performance that much, use it on per form post basis) before inserting to database ? I've been reading about pros and cons about whether to escape on input/output with majority says that we should escape on output only. But then again, why allow strings like <a href="javascript:stealCookie()">Click Me</a> to be saved in the database at all? The one thing I don't like is javascript: and such will be converted to [removed]. Can I extend the CI's security core $_never_allowed_str arrays so that the never allowed strings return empty rather than [removed]. The best reasonable wrongdoing example of this I've read is if a user has password of javascript:123 it will be cleaned into [removed]123 which means string like this document.write123 will also pass as the user's password. Then again, what is the odds of that to happen and even if it happens, I can't think of any real harm that can do to the site. Thanks

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• UIDs for data objects in MySQL

  - by Callash

  Hi there, I am using C++ and MySQL. I have data objects I want to persist to the database. They need to have a unique ID for identification purposes. The question is, how to get this unique ID? Here is what I came up with: 1) Use the auto_increment feature of MySQL. But how to get the ID then? I am aware that MySQL offers this "SELECT LAST_INSERT_ID()" feature, but that would be a race condition, as two objects could be inserted quite fast after each other. Also, there is nothing else that makes the objects discernable. Two objects could be created pretty much at the same time with exactly the same data. 2) Generate the UID on the C++ side. No dice, either. There are multiple programs that will write to and read from the database, who do not know of each other. 3) Insert with MAX(uid)+1 as the uid value. But then, I basically have the same problem as in 1), because we still have the race condition. Now I am stumped. I am assuming that this problem must be something other people ran into as well, but so far, I did not find any answers. Any ideas?

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• Telling me my stored procedure isn't declared

  - by Scott

  Here is where the error is occuring in the stack: public static IKSList<DataParameter> Search(int categoryID, int departmentID, string title) { Database db = new Database(DatabaseConfig.CommonConnString, DatabaseConfig.CommonSchemaOwner, "pkg_data_params_new", "spdata_params_search"); db.AddParameter("category_id", categoryID); db.AddParameter("department_id", departmentID); db.AddParameter("title", title, title.Length); DataView temp = db.Execute_DataView(); IKSList<DataParameter> dps = new IKSList<DataParameter>(); foreach (DataRow dr in temp.Table.Rows) { DataParameter dp = new DataParameter(); dp.Load(dr); dps.Add(dp); } return dps; } And here is the error text: ORA-06550: line 1, column 38: PLS-00302: component 'SPDATA_PARAMS_SEARCH' must be declared ORA-06550: line 1, column 7: PL/SQL: Statement ignored Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.OracleClient.OracleException: ORA-06550: line 1, column 38: PLS-00302: component 'SPDATA_PARAMS_SEARCH' must be declared ORA-06550: line 1, column 7: PL/SQL: Statement ignored Source Error: Line 161: db.AddParameter("title", title, title.Length); Line 162: Line 163: DataView temp = db.Execute_DataView(); Line 164: Line 165: IKSList dps = new IKSList(); My webconfig is pointing to the correct place and everything so idk where this is coming from.

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• Need help managing MySql connections

  - by David Jenings

  I'm having trouble finding a clear explanation of connection pooling. I'm building an app using the .NET connector I downloaded from mysql.com. The app only needs one db connection but will be running simultaneously on about 6 machines on my network. Normally, I'd create the connection at startup and just leave it. But I'm seeing lots of posts from people who say that's bad practice. Also I'm concerned about timeouts. My app will run 24/7 and there may be extended periods without database activity. I'm leaning toward the following: using (MySqlConnection conn = new MySqlConnection(connStr)) { conn.Open(); // use connection } But I'm not sure I understand what's going on in the background. Is this actually closing the connection and allowing gc to kill the object, or is there a built in pooling behavior that preserves the object and redelivers it the next time I try to create one? I certainly don't want the app reauthenticating across the network every time I hit the database. Can anyone offer me some advise?

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• WP_Insert_Post and GUID Issue [Wordpress]

  - by morningglory

  Hello, I have a posting form at my theme. I used wp_insert_post there. My code looks like this $post = array( 'ID' => '', 'post_author' => $post_author, 'post_category' => $post_category, 'post_content' => $post_content, 'post_title' => $post_title, 'post_status' => 'publish', ); $post_id = wp_insert_post($post); $fullpost = get_post($post_id); wp_redirect($fullpost->guid); Everything works fine. But when it's inserted to the database, at the GUID field, the entry format is like this permalinks_structure/id. So if my permalinks_structure is like /category/id , it become like http://www.example.com/uncategorized/1. So the problem is, if i post through wordpress admin panel, GUID of the post is http://www.example.com?p=1 . So my post database GUID become mess, because if i want to change permalinks_structure , the post which becomes from outside form will follow the structure. What I want to do is, I want to get the GUID like that I posted through admin panel which is http://www.example.com?p=1 How can i do it ? Please point me out. Thank you.

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• IE8 and below <input type="image"> value work around

  - by kielie

  Hi guys, I have a slight problem, I am trying to capture the input of two buttons, one yes, one no, into a database but for some reason the database doesn't always show the value of the button clicked, it just shows up blank. <form action="refer.php" method="post" id="formID" > <div class="prompt_container" style="float: left;"> <span class="prompt_item"><input type="image" src="images/yes.jpg" alt="submit" value="yes" onclick="this.disabled=true,this.form.submit();" /></span> <input type="hidden" name="refer" value="yes"> </div> </form> <form action="thank_you.php" method="post" id="formID" > <div class="prompt_container" style="float: right;"> <span class="prompt_item"><input type="image" src="images/no.jpg" alt="submit" value="no" onclick="this.disabled=true,this.form.submit();" /></span> <input type="hidden" name="refer" value="no" > </div> </form> Apparently anything lower than IE8 will ignore the value attribute of all form inputs. How could I get this to work properly in all browsers? jQuery or Javascript maybe?

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• Complicated API issue with calling assemblies dynamically?

  - by Stefanos Tses

  I have an interesting challenge that I'm wondering if anyone here can give me some direction. I'm writing a .Net windows forms application that runs on a network and uses an SQL Server to save and pull data. I want to offer a mini "plugin" API, where developers can build their own assemblies and implement a specific interface (IDataManipulate). These assemblies then can be used by my application to call the interface functions and do something. I can create assemblies using my API, copy the file to a folder in my local hard drive and configure my application to use Reflection to call a specific function from the implemented interface (IDataManipulate.Execute). The problem: Since the application will be installed in multiple workstations in the network, is impossible to copy the plugin dlls the users will create to each machine. Solutions I tried: Solution 1 Copy the API dll to a network share. Problem: Requires AllowPartiallyTrustedCallersAttribute, which requires .Net singing, which I can't force from my users. Solution 2 (preferred) Serialize the dll object, save it to the database, deserialize it and call IDataManipulate.Execute. Problem: After deserialization, I try cast it to a IDataManipulate object but returns an error looking for the actual dll file. Solution 3 Save the dll bytes as byte[] to the database and recreate the dll at the local PC every time the user starts my application. Problem: Dll may have dependencies, which I don't know if I can detect. Any suggestions will be greatly appreciated. Thanks

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• Data base design with Blob

  - by mmuthu

  Hi, I have a situation where i need to store the binary data into database as blob column. There are three different table exists in my database where in i need to store a blob data for each record. Not every record will have the blob data all the time. It is time and user based. The table one will have to store the *.doc files almost for all the record The table two will have to store the *.xml optionally. The table three will have to store images (not sure what is frequency, etc) Now my questions is whether it is a good idea to maintain a separate table to store the blob data pointing it to the respective table PK's (Yes, there will be no FK's and assuming program will maintain it). It will be some thing like below, BLOB|PK_ID|TABLE_NAME Alternatively, is it a good idea to keep the blob column in respective tables. As for as my application runtime is concerned, The table 2 will be read very frequently. Though the blob column will not be required. The table 2 record will gets deleted frequently. Similarly other blob data in respective table will not be accessed frequently. All of the blob content will be read on-demand basis. I'm thinking first approach will work better for me. What do you guys think? Btw, I'm using Oracle.

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• Object Reference with TimeSpan/DateTime

  - by user1732039

  When creating an appointment i want to send an email out to the patient with details like Time, Date etc. I know the email service i have created works (i have tested it by hardcoding strings into the method with the problem. The Problem is that i am getting Object reference issues with converting the Time and Date to a string. It does create the appointment data in the database correctly (time and date). User_Doctor thisDoc = user_DoctorComboBox.SelectedItem as User_Doctor; User_Patient thisPatient = appointment_Patient_autoComplete.SelectedItem as User_Patient; Appointment App = AppointmentSlots.SelectedItem as Appointment; DateTime date = (DateTime)datePickerAppointment.SelectedDate; TimeSpan timeslot = App.Time; //For Emailing Patients string fullname = thisPatient.PatientName + " " + thisPatient.PatientSurname; string mestime = timeslot.ToString("HH:mm"); string mesdate = date.ToString("MM/dd/yyyy"); string email = thisPatient.aspnet_Users.aspnet_Membership.LoweredEmail; EmailServiceClient em = new EmailServiceClient(); em.createMessageAsync(email, "Upcomming Appointment", fullname, mestime, mesdate, thisDoc.aspnet_Users.UserName, true); The problem occures with the strings mestime and mesdate, as well as with getting the email of the user from the database (again this exists in the db, as a nvar)

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• SQL Server: Why use shorter VARCHAR(n) fields?

  - by chryss

  It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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• strange doctrine update problem

  - by larryzhao

  Hi, guys, I have a simple table like following: class SnookerCurrentInfo extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('current_frame_id', 'integer', 4, array('notnull' => 'false')); $this->hasColumn('current_player_id', 'integer', 4, array('notnull' => 'false')); $this->hasColumn('current_score1', 'integer', 4, array('notnull' => 'false')); $this->hasColumn('current_score2', 'integer', 4, array('notnull' => 'false')); } public function setUp(){ $this->setTableName('snooker_current_info'); } } and I would like to keep only one entry in this table. So every time the value is changed I read the entry with id = 1 out and change the object and execute save. like the following: $info = Doctrine::getTable('SnookerCurrentInfo')->find(1); $info->current_frame_id = $jsonInfo['current_frame_id']; $info->current_player_id = $jsonInfo['current_player_id']; $info->current_score1 = $jsonInfo['current_score1']; $info->current_score2 = $jsonInfo['current_score2']; $info->save(); but the strange thing is, I try to make it clear. Let's say at first, the entry is (30, 1, 1, 0) and I switch player, so update the entry to (30, 2, 1, 0). and I switch the player back again, so the entry should be updated to (30, 1, 1, 0), but this is not affected to the database!! In the database, the entry still remains as (30, 2, 1, 0)!!!! But if after (30, 2, 1, 0), I update the score to (30, 2, 1, 1) and then switch the player back (30, 1, 1, 1) then this is ok. What's that? How should I deal with it? Thanks for a lot helping, really urgent!!

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• A good(elegant) way to retrieve records with counts.

  - by user93422

  Context: ASP.NET MVC 2.0, C#, SQL Server 2007, IIS7 I have 'scheduledMeetings' table in the database. There is a one-to-many relationship: scheduledMeeting - meetingRegistration So that you could have 10 people registered for a meeting. meetingRegistration has fields Name, and Gender (for example). I have a "calendar view" on my site that shows all coming events, as well as gender count for each event. At the moment I use Linq to Sql to pull the data: var meetings = db.Meetings.Select( m => new { MeetingId = m.Id, Girls = m.Registrations.Count(r => r.Gender == 0), Boys = m.Registrations.Count(r=>r.Gender == 1) }); (actual query is half-a-page long) Because there is anonymous type use going on I cant extract it into a method (since I have several different flavors of calendar view, with different information on each, and I dont want to create new class for each). Any suggestions on how to improve this? Is database view is the answer? Or should I go ahead and create named-type? Any feedback/suggestions are welcome. My DataLayer is huge, I want to trim it, just dont know how. Pointers to a good reading would be good too.

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• How to map this class in NHibernate (not FluentNHibernate)?

  - by JMSA

  Suppose I have a database like this: This is set up to give role-wise menu permissions. Please note that, User-table has no direct relationship with Permission-table. Then how should I map this class against the database-tables? class User { public int ID { get; set; } public string Name { get; set; } public string Username { get; set; } public string Password { get; set; } public bool? IsActive { get; set; } public IList<Role> RoleItems { get; set; } public IList<Permission> PermissionItems { get; set; } public IList<string> MenuItemKeys { get; set; } } This means, (1) Every user has some Roles. (2) Every user has some Permissions (depending on to Roles). (3) Every user has some permitted MenuItemKeys (according to Permissions). How should my User.hbm.xml look like?

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• Linq based generic alternate to Predicate<T>?

  - by Eric

  I have an interface called ICatalog as shown below where each ICatalog has a name and a method that will return items based on a Predicate<Item> function. public interface ICatalog { string Name { get; } IEnumerable<IFamily> GetItems(Predicate<Item> predicate); } A specific implementation of a catalog may be linked to catalogs in various format such as XML, or a SQL database. With an XML catalog I end up deserializing the entire XML file into memory, so testing each item with the predicate function does does not add a whole lot more overhead as it's already in memory. Yet with the SQL implementation I'd rather not retrieve the entire contents of the database into memory, and then filter the items with the predicate function. Instead I'd want to find a way to somehow pass the predicate to the SQL server, or somehow convert it to a SQL query. This seems like a problem that can be solved with Linq, but I'm pretty new to it. Should my interface return IQueryable instead?

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• What is the best way to embed SQL in VB.NET.

  - by Amy P

  I am looking for information on the best practices or project layout for software that uses SQL embedded inside VB.NET or C#. The software will connect to a full SQL DB. The software was written in VB6 and ported to VB.NET, we want to update it to use .NET functionality but I am not sure where to start with my research. We are using Visual Studio 2005. All database manipulations are done from VB. Update: To clarify. We are currently using SqlConnection, SqlDataAdapter, SqlDataReader to connect to the database. What I mean by embed is that the SQL stored procedures are scripted inside our VB code and then run on the db. All of our tables, stored procs, views, etc are all manipulated in the VB code. The layout of our code is quite messy. I am looking for a better architecture or pattern that we can use to organize our code. Can you recommend any books, webpages, topics that I can google, etc to help me better understand the best way for us to do this.

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• Abstract Design Pattern implementation

  - by Pathachiever11

  I started learning design patterns a while ago (only covered facade and abstract so far, but am enjoying it). I'm looking to apply the Abstract pattern to a problem I have. The problem is: Supporting various Database systems using one abstract class and a set of methods and properties, which then the underlying concrete classes (inheriting from abstract class) would be implementing. I have created a DatabaseWrapper abstract class and have create SqlClientData and MSAccessData concrete class that inherit from the DatabaseWrapper. However, I'm still a bit confused about how the pattern goes as far as implementing these classes on the Client. Would I do the following?: DatabaseWrapper sqlClient = new SqlClientData(connectionString); This is what I saw in an example, but that is not what I'm looking for because I want to encapsulate the concrete classes; I only want the Client to use the abstract class. This is so I can support for more database systems in the future with minimal changes to the Client, and creating a new concrete class for the implementations. I'm still learning, so there might be a lot of things wrong here. Please tell me how I can encapsulate all the concrete classes, and if there is anything wrong with my approach. Many Thanks! PS: I'm very excited to get into software architecture, but still am a beginner, so take it easy on me. :)

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• A self-creator: What pattern is this? php

  - by user151841

  I have several classes that are basically interfaces to database rows. Since the class assumes that a row already exists ( __construct expects a field value ), there is a public static function that allows creation of the row and returns an instance of the class. Here's a pseudo-code example : class fruit { public $id; public function __construct( $id ) { $this->id = $id; $sql = "SELECT * FROM Fruits WHERE id = $id"; ... $this->arrFieldValues[$field] = $row[$value]; } public function __get( $var ) { return $this->arrFieldValues[$var]; } public function __set( $var, $val ) { $sql = "UPDATE fruits SET $var = $val WHERE id = $this->id"; } public static function create( $id ) { $sql = "INSERT INTO Fruits ( fruit_name ) VALUE ( '$fruit' )"; $id = mysql_insert_id(); $fruit = & new fruit($id); return $fruit; } } $obj1 = fruit::create( "apple" ); $obj2 = & new fruit( 12 ); What is this pattern called? Edit: I changed the example to one that has more database-interface functionality. For most of the time, this kind of class would be instantiated normally, through __construct(). But sometimes when you need to create a new row first, you would call create().

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