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  • Android ExpandableListView From Database

    - by SterAllures
    I want to create a two level ExpandableListView from a local database. The group level I want to get the names from the database Category table category_id | name ------------------- 1 | NameOfCategory the children level I want to get the names from the List table list_id | name | foreign_category_id -------------------------------- 1 | Listname | 1 I've got a method in DatabaseDAO to get all the values from the table public List<Category> getAllCategories() { database = dbHelper.getReadableDatabase(); List<Category> categories = new ArrayList<Category>(); Cursor cursor = database.query(SQLiteHelper.TABLE_CATEGORY, null, null, null, null, null, null); cursor.moveToFirst(); while(!cursor.isAfterLast()) { Category category = cursorToCategory(cursor); categories.add(category); cursor.moveToNext(); } cursor.close(); return categories; } Now adding the names to the group level is easy I do it the following way: ArrayList<String> groups; for(Category c : databaseDao.getAllCategories()) { groups.add(c.getName()); } Now I want to add the children to the ExpandableListView in the following array ArrayList<ArrayList<ArrayList<String>>> children;. How do I get the children under the correct group name? I think it has to do somenthing with groups.indexOf() but in the list table I only have a foreign category_id and not the actual name.

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  • regex to escape non-html tags' angle brackets

    - by suad
    Hi I have an html based text (with html tags), I want to find words that occur within angle brackets and replace the brackets with < and > or even when angle brackets are used as math symobls e.g: String text= "Hello, <b> Whatever <br/> <table> <tr> <td width="300px"> 1<2 This is a <test> </td> </tr> </table>"; I want this to be : Hello, <b> Whatever <br/> <table> <tr> <td width="300px"> 1&lt;2 This is a &lt;test&gt; </td> </tr> </table> THANKS in advance

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  • Vertically Merge Multiple Tables in MySQL by Joint Primary Key

    - by world
    Hello, I'll attempt to make my question as clear as possible. I'm fairly unexperienced with SQL, only know the really basic queries. In order to have a better idea I'd been reading the MySQL manual for the past few days, but I couldn't really find a concrete solution and my needs are quite specific. I've got 3 MySQL MyISAM tables: table1, table2 and table3. Each table has an ID column (ID, ID2, ID3 respectively), and different data columns. For example table1 has [ID, Name, Birthday, Status, ...] columns, table2 has [ID2, Country, Zip, ...], table3 has [ID3, Source, Phone, ...] you get the idea. The ID, ID2, ID3 columns are common to all three tables... if there's an ID value in table1 it will also appear in table2 and table3. The number of rows in these tables is identical, about 10m rows in each table. What I'd like to do is create a new table that contains (most of) the columns of all three tables and merge them into it. The dates, for instance, must be converted because right now they're in VARCHAR YYYYMMDD format. Reading the MySQL manual I figured STR_TO_DATE() would do the job, but I don't know how to write the query itself in the first place so I have no idea how to integrate the date conversion. So basically, after I create the new table (which I do know how to do), how can I merge the three tables into it, integrating into the query the date conversion?

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  • Support for encoding query string or POST data in YUI ?

    - by faB
    How do you encode a javascript object/hash (pairs of properties and values) into a URL-encoded query string with YUI (2.7.0 or 3.0.0 Beta) ? I want to do the equivalent of Object.toQueryString() from Prototype: I need this to encode parameters for GET and POST requests with YAHOO.util.Connect. It turns out YAHOO.util.Connect has a setForm() method to serialize a form but that still leaves me out cold to encode parameters for GET requests, or the 4th parameter of YAHOO.util.Connect.asyncRequest() to pass post data.

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  • Injecting the mailer service, got "The service definition 'mailer' does not exist"?

    - by Gremo
    This is the class where the service mailer should be injected: namespace Gremo\SkebbyBundle\Transport; use Swift_Mailer; use Gremo\SkebbyBundle\Message\AbstractSkebbyMessage; class MailerTransport extends AbstractSkebbyTransport { /** * @var \Swift_Mailer */ private $mailer; public function __construct(Swift_Mailer $mailer) { $this->mailer = $mailer; } /** * @param \Gremo\SkebbyBundle\Message\AbstractSkebbyMessage $message * @return void */ public function executeTransport(AbstractSkebbyMessage $message) { /* ... */ } } Service id is gremo_skebby.transport.mailer, placed inside mailer.xml file: <parameters> <parameter key="gremo_skebby.converter.swift_message.class"> Gremo\SkebbyBundle\Converter\SwiftMessageConverter </parameter> <parameter key="gremo_skebby.transport.mailer.class"> Gremo\SkebbyBundle\Transport\MailerTransport </parameter> </parameters> <services> <service id="gremo_skebby.converter.swift_message" class="%gremo_skebby.converter.swift_message.class%" public="false" /> <service id="gremo_skebby.transport.mailer" class="%gremo_skebby.transport.mailer.class%" public="false" parent="gremo_skebby.tranport.abstract_transport"> <argument type="service" id="mailer" /> </service> </services> When i try to inject the gremo_skebby.transport.mailer into another service (an helper) i get: Symfony\Component\DependencyInjection\Exception\InvalidArgumentException : The service definition "mailer" does not exist. That is strange, because command php app/console container:debug shows that the mailer service actually exists: mailer container Swift_Mailer I'm loading mailer.xml file dynamically by the extension: if(in_array($configs['transport'], array('http', 'rest', 'mailer'))) { $loader->load('transport.xml'); $loader->load($configs['transport'] . '.xml'); $container->setAlias('gremo_skebby.transport', 'gremo_skebby.transport.' . $configs['transport']); } $loader->load('skebby.xml'); ... and gremo_skebby.transport service is injected into gremo_skebby.skebby service (skebby.xml): <parameters> <parameter key="gremo_skebby.skebby.class"> Gremo\SkebbyBundle\Skebby </parameter> </parameters> <services> <service id="gremo_skebby.skebby" class="%gremo_skebby.skebby.class%"> <argument type="service" id="gremo_skebby.transport" /> </service> </services> A quick test is giving me the same InvalidArgumentException: public function testSkebbyWithMailerTransport() { $loader = new GremoSkebbyExtension(); $container = new ContainerBuilder(); $config = $this->getEmptyConfiguration(); $loader->load(array($config), $container); $this->assertTrue($container->hasDefinition('gremo_skebby.transport.mailer')); $this->assertTrue($container->hasDefinition('gremo_skebby.skebby')); $this->assertInstanceOf('Gremo\SkebbyBundle\Skebby', $container->get('gremo_skebby.skebby')); }

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  • mysql and trigger usage question

    - by dhruvbird
    I have a situation in which I don't want inserts to take place (the transaction should rollback) if a certain condition is met. I could write this logic in the application code, but say for some reason, it has to be written in MySQL itself (say clients written in different languages will be inserting into this MySQL InnoDB table) [that's a separate discussion]. Table definition: CREATE TABLE table1(x int NOT NULL); The trigger looks something like this: CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN NEW.x = NULL; END IF; END; I am guessing it could also be written as(untested): CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN ROLLBACK; END IF; END; But, this doesn't work: CREATE TRIGGER t1 BEFORE INSERT ON table1 ROLLBACK; You are guaranteed that: Your DB will always be MySQL Table type will always be InnoDB That NOT NULL column will always stay the way it is Question: Do you see anything objectionable in the 1st method?

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  • Please help optimizing a long running query (left outer join, with 2 subqueries)

    - by 46and2
    Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

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  • How to store a function pointer in C#

    - by Joshua
    Let's say I want to store a group of function pointers in a List<(*func), and then later call them, perhaps even with parameters... Like if I stored in a Dict<(*func), object[] params could I call the func with the parameters? How would I do this?

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  • Hibernate: deletes not cascading for self-referencing entities

    - by jwaddell
    I have the following (simplified) Hibernate entities: @Entity @Table(name = "package") public abstract class Package { protected Content content; @ManyToOne(cascade = {javax.persistence.CascadeType.ALL}) @JoinColumn(name = "content_id") @Fetch(value = FetchMode.JOIN) public Content getContent() { return content; } public void setContent(Content content) { this.content = content; } } @Entity @Table(name = "content") public class Content { private Set<Content> subContents = new HashSet<Content>(); @ManyToMany(fetch = FetchType.EAGER) @JoinTable(name = "subcontents", joinColumns = {@JoinColumn(name = "content_id")}, inverseJoinColumns = {@JoinColumn(name = "elt")}) @Cascade(value = {org.hibernate.annotations.CascadeType.DELETE, org.hibernate.annotations.CascadeType.REPLICATE}) @Fetch(value = FetchMode.SUBSELECT) public Set<Content> getSubContents() { return subContents; } public void setSubContents(Set<Content> subContents) { this.subContents = subContents; } } So a Package has a Content, and a Content is self-referencing in that it has many sub-Contents (which may contain sub-Contents of their own etc). The relationships are required to be ManyToOne (Package to Content) and ManyToMany (Content to sub-Contents) but for the case I am currently testing each sub-Content only relates to one Package or Content. The problem is that when I delete a Package and flush the session, I get a Hibernate error stating that I'm violating a foreign key constraint on table subcontents, with a particular content_id still referenced from table subcontents. I've tried specifically (recursively) deleting the Contents before deleting the Package but I get the same error. Is there a reason why this entity tree is not being deleted properly?

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  • Adding space BETWEEN cells in TableCell()

    - by user279521
    My code is below. I want to add space between cells in tableCell() something the equivalent of <td></td>&nbsp;&nbsp;<td></td> I am NOT looking for cellpadding or cellspacing because they both add space between the left cell border and the left table border (wall); I want to add space between two CELLS, not the table and the cell; protected void Page_Init(object sender, EventArgs e) { Table tb = new Table(); tb.ID = "tb1"; for (int i = 0; i < iCounter; i++) { TableRow tr = new TableRow(); TextBox tbox = new TextBox(); tbox.ID = i.ToString(); TableCell tc = new TableCell(); tc.Controls.Add(tbox); tr.Cells.Add(tc); tb.Rows.Add(tr); } pnlScheduler.Controls.Add(tb); } Any ideas?

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  • How to Access value of dynamically created control?

    - by sharad
    i have asp.net web application in which i need to create form dynamically depend upon table which user selected.however,i created form dynamically with it's control like text box,drop downlist etc. but not able to access those controls at particular button click event. My form scenario is like this: i have dropdownlist in which i display list of tables,button control say display( on click event which i redirect page with some addition in querystring so that at page init it dynamically genrate controls) and another button control which used to access this controls value say Submit and store in database. This is my code: At Display button Click event: Response.Redirect("dynamic_main.aspx?mode=edit&tablename=" + CMBTableList.SelectedItem.ToString()); This is code For page.Init level if (Request.QueryString["mode"] != null) { if (Request.QueryString["mode"].ToString() == "edit") { Session["tablename"] = Request.QueryString["tablename"].ToString(); // if (Session["tablename"].ToString() == CMBTableList.SelectedItem.ToString()) //{ createcontrol(Session["tablename"].ToString()); // } } } i have used createcontrol() which genrate controls Code For Submit Button: string[] contid=controlid.Value.Split(','); MasterPage ctl00 = FindControl("ctl00") as MasterPage; ContentPlaceHolder cplacehld = ctl00.FindControl("ContentPlaceHolder2") as ContentPlaceHolder; Panel panel1 = cplacehld.FindControl("plnall") as Panel; Table tabl1 = panel1.FindControl("id1") as Table; foreach (string sin in contid) { string splitcvalu = sin.Split('_')[0].ToString(); ControlsAccess contaccess = new ControlsAccess(); if (splitcvalu.ToString() == "txt") { TextBox txt = (TextBox)tabl1.FindControl(sin.ToString()); //TextBox txt = cplacehld.FindControl(sin.ToString()) as TextBox; val = txt.ID; } else { DropDownList DDL = cplacehld.FindControl(sin.ToString()) as DropDownList; } } Here i am no able to access this textbox or drop downlist.i am getting id of particular control from hidden field controlid in which i have stored it during genrating controls. i have used findcontrol() it works in case of finding masterpage,contentplaceholder,table etc. but in case of textbox or other control it doesnt work it shows it returns null. Anyone can help me. Thanks

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  • why DataColumn AllowDbNull is true even if oracle db does not allow null

    - by matti
    Hi. I have column SomeId in table SomeLink. When I look with tOra or Sql Plus Worksheet both state: tOra: Column name Data type Default Null Comment SOMEID INTEGER {null} NOT NULL {null} Sql Plus: SOMEID NOT NULL NUMBER(38) I have authored a method that's intended to give default values to all NOT NULL fields that don't have values: public static void GetDefaultValuesForNonNullColumns(DataRow row) { foreach(DataColumn col in row.Table.Columns) { if (Convert.IsDBNull(row[col]) && !col.AllowDBNull) { if (ColumnIsNumeric(col.DataType)) row[col] = 0; else if (col.DataType == typeof(DateTime)) row[col] = DateTime.Now; else if (col.DataType == typeof(String)) row[col] = string.Empty; else if (col.DataType == typeof(Char)) row[col] = ' '; else throw new Exception(string.Format("Unsupported column type: {0}", col.DataType)); } } } When SOMEID is handled in loop the AllowDBNull = true. I really can't understand. The table is created in DataSet like this: _someLinkAdptr = _dbFactory.CreateDataAdapter(); _someLinkAdptr.SelectCommand = _dbFactory.CreateCommand(); _someLinkAdptr.SelectCommand.Connection = _cnctn; _someLinkAdptr.SelectCommand.CommandText = GetSomeLinkSelectTxtAndParams(_someLinkAdptr.SelectCommand, UndefinedValue.ToString(), UndefinedValue.ToString()); Select command returns no rows. The idea is that I can then use commandbuilder to get InsertCommand without building it myself. The row is added to dataset's table like this: private static void CreateDocLink(int anId, int anotherId) { DataRow row = _someDataSet.Tables["SomeLink"].NewRow(); row["AnId"] = anId; row["AnotherId"] = anotherId; Utility.GetDefaultValuesForNonNullColumns(row); _someDataSet.Tables["SomeLink"].Rows.Add(row); } When DataAdapter is updated to oracle db I get: ORA-01400: cannot insert NULL into (SOMESCHEMA.SOMELINK.SOMEID) Cheers & BR -Matti

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  • Why are virtual methods considered early bound?

    - by AspOnMyNet
    One definition of binding is that it is the act of replacing function names with memory addresses. a) Thus I assume early binding means function calls are replaced with memory addresses during compilation process, while with late binding this replacement happens during runtime? b) Why are virtual methods also considered early bound (thus the target method is found at compile time, and code is created that will call this method)? As far as I know, with virtual methods the call to actual method is resolved only during runtime and not compile time?! thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) v-table calls are neither early nor late bound. Instead there's an offset into a table of function pointers. The offset is fixed at compile time, but which table the function pointer is chosen from depends on the runtime type of the object (the object contains a hidden pointer to its v-table), so the final function address is found at runtime. But assuming the object of type T is created via reflection ( thus app doesn’t even know of existence of type T ), then how can at compile time exist an entry point for that type of object?

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  • Ajax heavy JS apps using excessive amounts of memory over time.

    - by Shane Reustle
    I seem to have some pretty large memory leaks in an app that I am working on. The app itself is not very complex. Every 15 seconds, the page requests approx 40kb of JSON from the server, and draws a table on the page using it. It is cheaper to draw the table over because the data is usually always new. I am attaching a few events to the table, approx 5 per line, 30 lines in the table. I used jQuery's .html() method to put the new html into the container and overwrite the existing. I do this specifically so that jQuery's special cleanup functions go in and attempt to detach all events on the elements in the element that it is overwriting. I then also delete the large variables of html once they are sent to the DOM using delete my_var. I have checked for circular references and attached events that are never cleared a few times, but never REALLY dug into it. I was wondering if someone could give me a few pointers on how to optimize a very heavy app like this. I just picked up "High Performance Javascript" by Nicholas Zakas, but didn't have much time to get into it yet. To give an idea on how much memory this is using, after 4~ hours, it is using about 420,000k on chrome, and much more on Firefox or IE. Thanks!

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  • Mysql Database Question about Large Columns

    - by murat
    Hi, I have a table that has 100.000 rows, and soon it will be doubled. The size of the database is currently 5 gb and most of them goes to one particular column, which is a text column for PDF files. We expect to have 20-30 GB or maybe 50 gb database after couple of month and this system will be used frequently. I have couple of questions regarding with this setup 1-) We are using innodb on every table, including users table etc. Is it better to use myisam on this table, where we store text version of the PDF files? (from memory usage /performance perspective) 2-) We use Sphinx for searching, however the data must be retrieved for highlighting. Highlighting is done via sphinx API but still we need to retrieve 10 rows in order to send it to Sphinx again. This 10 rows may allocate 50 mb memory, which is quite large. So I am planning to split these PDF files into chunks of 5 pages in the database, so these 100.000 rows will be around 3-4 million rows and couple of month later, instead of having 300.000-350.000 rows, we'll have 10 million rows to store text version of these PDF files. However, we will retrieve less pages, so again instead of retrieving 400 pages to send Sphinx for highlighting, we can retrieve 5 pages and it will have a big impact on the performance. Currently, when we search a term and retrieve PDF files that have more than 100 pages, the execution time is 0.3-0.35 seconds, however if we retrieve PDF files that have less than 5 pages, the execution time reduces to 0.06 seconds, and it also uses less memory. Do you think, this is a good trade-off? We will have million of rows instead of having 100k-200k rows but it will save memory and improve the performance. Is it a good approach to solve this problem and do you have any ideas how to overcome this problem? The text version of the data is used only for indexing and highlighting. So, we are very flexible. Thanks,

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  • Optimization headers for UITableView?

    - by Pask
    I have an optimization problem for the headers of a table with plain style. If I use the standard view for the table (the classic gray with titles set by titleForHeaderInSection:) everything is ok and the scrolling is smooth and immediate. When, instead, use this code to set my personal view: - (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section { return [self headerPerTitolo:[titoliSezioni objectAtIndex:section]]; } - (UIImageView *)headerPerTitolo:(NSString *)titolo { UIImageView *headerView = [[[UIImageView alloc] initWithFrame:CGRectMake(10.0, 0.0, 320.0, 44.0)] autorelease]; headerView.image = [UIImage imageNamed:kNomeImmagineHeader]; headerView.alpha = kAlphaSezioniTablePlain; UILabel * headerLabel = [[[UILabel alloc] initWithFrame:CGRectZero] autorelease]; headerLabel.backgroundColor = [UIColor clearColor]; headerLabel.opaque = NO; headerLabel.textColor = [UIColor whiteColor]; headerLabel.font = [UIFont boldSystemFontOfSize:16]; headerLabel.frame = CGRectMake(10.0,-11.0, 320.0, 44.0); headerLabel.textAlignment = UITextAlignmentLeft; headerLabel.text = titolo; [headerView addSubview:headerLabel]; return headerView; } scrolling is jerky and not immediate (sliding the finger on the screen does not match an immediate shift of the table). I do not know what caused this problem, maybe the fact that every time the method viewForHeaderInSection: is called, the code runs to create a new UIImageView. I tried many ways to solve the problem, such as creating an array of all the necessary view: apart from more time spent loading at startup, there is a continuing problem of low reactivity of the table. 've Attempted by reducing the size of UIImageView positioned from about 66 KB to 4 KB: not only has a deterioration in quality of colors (which distorts a bit 'original graphics), but ... the problem persists! Perhaps you have suggestions about it, or know me obscure techniques that enable me to optimize this aspect of my application ... I apologize for my English, I used Google for translation.

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  • Using RhinoMocks, how do you mock or stub a concrete class without an empty constructor?

    - by Mark Rogers
    Mocking a concrete class with Rhino Mocks seems to work pretty easy when you have an empty constructor on a class: public class MyClass{ public MyClass() {} } But if I add a constructor that takes parameters and remove the one that doesn't take parameters: public class MyClass{ public MyClass(MyOtherClass instance) {} } I tend to get an exception: System.MissingMethodException : Can't find a constructor with matching arguments I've tried putting in nulls in my call to Mock or Stub, but it doesn't work. Can I create mocks or stubs of concrete classes with Rhino Mocks, or must I always supply (implicitly or explicitly) a parameter-less constructor?

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  • How to define a "complicated" ComputedColumn in SQL Server?

    - by Slauma
    SQL Server Beginner question: I'm trying to introduce a computed column in SQL Server (2008). In the table designer of SQL Server Management Studio I can do this, but the designer only offers me one single edit cell to define the expression for this column. Since my computed column will be rather complicated (depending on several database fields and with some case differentiations) I'd like to have a more comfortable and maintainable way to enter the column definition (including line breaks for formatting and so on). I've seen there is an option to define functions in SQL Server (scalar value or table value functions). Is it perhaps better to define such a function and use this function as the column specification? And what kind of function (scalar value, table value)? To make a simplified example: I have two database columns: DateTime1 (smalldatetime, NULL) DateTime2 (smalldatetime, NULL) Now I want to define a computed column "Status" which can have four possible values. In Dummy language: if (DateTime1 IS NULL and DateTime2 IS NULL) set Status = 0 else if (DateTime1 IS NULL and DateTime2 IS NOT NULL) set Status = 1 else if (DateTime1 IS NOT NULL and DateTime2 IS NULL) set Status = 2 else set Status = 3 Ideally I would like to have a function GetStatus() which can access the different column values of the table row which I want to compute the value of "Status" for, and then only define the computed column specification as GetStatus() without parameters. Is that possible at all? Or what is the best way to work with "complicated" computed column definitions? Thank you for tips in advance!

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  • how to Compute the average probe length for success and failure - Linear probe (Hash Tables)

    - by fang_dejavu
    hi everyone, I'm doing an assignment for my Data Structures class. we were asked to to study linear probing with load factors of .1, .2 , .3, ...., and .9. The formula for testing is: The average probe length using linear probing is roughly Success-- ( 1 + 1/(1-L)**2)/2 or Failure-- (1+1(1-L))/2. we are required to find the theoretical using the formula above which I did(just plug the load factor in the formula), then we have to calculate the empirical (which I not quite sure how to do). here is the rest of the requirements **For each load factor, 10,000 randomly generated positive ints between 1 and 50000 (inclusive) will be inserted into a table of the "right" size, where "right" is strictly based upon the load factor you are testing. Repeats are allowed. Be sure that your formula for randomly generated ints is correct. There is a class called Random in java.util. USE it! After a table of the right (based upon L) size is loaded with 10,000 ints, do 100 searches of newly generated random ints from the range of 1 to 50000. Compute the average probe length for each of the two formulas and indicate the denominators used in each calculationSo, for example, each test for a .5 load would have a table of size approximately 20,000 (adjusted to be prime) and similarly each test for a .9 load would have a table of approximate size 10,000/.9 (again adjusted to be prime). The program should run displaying the various load factors tested, the average probe for each search (the two denominators used to compute the averages will add to 100), and the theoretical answers using the formula above. .** how do I calculate the empirical success?

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  • Database nesting layout confusion

    - by arzon
    I'm no expert in databases and a beginner in Rails, so here goes something which kinda confuses me... Assuming I have three classes as a sample (note that no effort has been made to address any possible Rails reserved words issue in the sample). class File < ActiveRecord::Base has_many :records, :dependent => :destroy accepts_nested_attributes_for :records, :allow_destroy => true end class Record < ActiveRecord::Base belongs_to :file has_many :users, :dependent => :destroy accepts_nested_attributes_for :users, :allow_destroy => true end class User < ActiveRecord::Base belongs_to :record end Upon entering records, the database contents will appear as such. My issue is that if there are a lot of Files for the same Record, there will be duplicate record names. This will also be true if there will be multiple Records for the same user in the the Users table. I was wondering if there is a better way than this so as to have one or more files point to a single Record entry and one or more Records will point to a single User. BTW, the File names are unique. Files table: id name 1 name1 2 name2 3 name3 4 name4 Records table: id file_id record_name record_type 1 1 ForDaisy1 ... 2 2 ForDonald1 ... 3 3 ForDonald2 ... 4 4 ForDaisy1 ... Users table: id record_id username 1 1 Daisy 2 2 Donald 3 3 Donald 4 4 Daisy Is there any way to optimize the database to prevent duplication of entries, or this should really the correct and proper behavior. I spread out the database into different tables to be able to easily add new columns in the future.

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  • Problem with LINQ in C#

    - by David Bonnici
    I am encountering a problem when using LINQ in C#, I am constantly getting "Specified cast is not valid". This is what I am trying to do. I create a class in which I declare all the columns of the table. [Table(Name="tbl_Aff")] public class Affiliate { [Column] public string name; [Column] public string firstname; [Column] public string surname; [Column] public string title; } I then declare a strongly typed DataContext in which I declare all Table collections as members of the context. public partial class Database : DataContext { public Table affiliate; public Database() : base(Settings.getConnectionString()) { } //This method gets the connection string by reading from an XML file. } public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Database database = new Database(); try { var q = from a in database.affiliate select a; foreach (var aff in q) // Here I get the error "Specified cast is not valid" { lblMessage.InnerHtml += aff.name + ""; } } catch (Exception ex) { System.Console.WriteLine(ex.Message); } } }

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  • Linq is returning too many results when joined

    - by KallDrexx
    In my schema I have two database tables. relationships and relationship_memberships. I am attempting to retrieve all the entries from the relationship table that have a specific member in it, thus having to join it with the relationship_memberships table. I have the following method in my business object: public IList<DBMappings.relationships> GetRelationshipsByObjectId(int objId) { var results = from r in _context.Repository<DBMappings.relationships>() join m in _context.Repository<DBMappings.relationship_memberships>() on r.rel_id equals m.rel_id where m.obj_id == objId select r; return results.ToList<DBMappings.relationships>(); } _Context is my generic repository using code based on the code outlined here. The problem is I have 3 records in the relationships table, and 3 records in the memberships table, each membership tied to a different relationship. 2 membership records have an obj_id value of 2 and the other is 3. I am trying to retrieve a list of all relationships related to object #2. When this linq runs, _context.Repository<DBMappings.relationships>() returns the correct 3 records and _context.Repository<DBMappings.relationship_memberships>() returns 3 records. However, when the results.ToList() executes, the resulting list has 2 issues: 1) The resulting list contains 6 records, all of type DBMappings.relationships(). Upon further inspection there are 2 for each real relationship record, both are an exact copy of each other. 2) All relationships are returned, even if m.obj_id == 3, even though objId variable is correctly passed in as 2. Can anyone see what's going on because I've spent 2 days looking at this code and I am unable to understand what is wrong. I have joins in other linq queries that seem to be working great, and my unit tests show that they are still working, so I must be doing something wrong with this. It seems like I need an extra pair of eyes on this one :)

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  • Spring Transactional Parameterized Test and Autowiring

    - by James Kingsbery
    Is there a way to get a class that extends AbstractTransactionalJUnit4SpringContexts to play nicely with JUnit's own @RunWith(Parameterized), so that fields marked as Autowired get wired in properly? @RunWith(Parameterized) public class Foo extends AbstractTransactionalJUnit4SpringContexts { @Autowired private Bar bar @Parameters public static Collection data() { // return parameters, following pattern in // http://junit.org/apidocs/org/junit/runners/Parameterized.html } @Test public void someTest(){ bar.baz() //NullPointerException } }

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  • symfony doctrine build-sql error

    - by user313571
    I have some big problems with symfony and doctrine at the beginning of a new project. I have created database diagram with mysql workbench, inserted the sql into phpmyadmin and then I've tried symfony doctrine:build-schema to generate the YAML schema. It generates a wrong schema (relations don't have on delete/on update) and after this I've tried symfony doctrine:build --sql and symfony doctrine:insert-sql The insert-sql statement generates error (can't create table ... failing query alter table add constraint ....), so I've decided to take a look over the generated sql and I've found out some differences between the sql generated from mysql workbench (which works perfect, including relations) and the sql generated by doctrine. I'll be short from now: I have to tables, EVENT and FORM and a 1 to n relation (each event may have multiple forms) so the correct constraint (generated with workbench) is ALTER TABLE `form` ADD CONSTRAINT `fk_form_event1` FOREIGN KEY (`event_id`) REFERENCES `event` (`id`) ON DELETE CASCADE ON UPDATE CASCADE; doctrine generated statement is: ALTER TABLE event ADD CONSTRAINT event_id_form_event_id FOREIGN KEY (id) REFERENCES form(event_id); It's totally reversed and I am sure here is the error. What should I do? It's also correct like this?

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