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  • how can I speed up insertion of many rows to a table via ADO.NET?

    - by jcollum
    I have a table that has 5 columns: AcctId (int), Address1 (varchar), Address2 (varchar), Person1 (varchar), Person2 (varchar) . I'm generating random data to insert into this table via a C# console application. I've tried doing this random data insert via SQL-Server and decided it was not a good solution -- SQL is not good at random on an each-row basis. Generating the random data -- 975k rows of it -- takes a minimal amount of time. It's in a List of custom objects. I need to take this random data and update many rows in the database with the new random data. I tried updating the rows one at a time, very slow because of the repeated searching of the List object in code. So I think the best approach is to put all the randomized data into a table in the database, then update all the other tables that use this data. I.e. UPDATE t SET t.Address1=d.Address1 FROM Table1 t INNER JOIN RandomizedData d ON d.AcctId = t.Acct_ID. The database is very un-normalized so this Acct data is sprinkled all over the place. I've got no control of the normalization. So, having decided to insert all of the randomized data into a single table, I set out to create insert scripts: USE TheDatabase Insert tmp_RandomizedData SELECT 1,'4392 EIGHTH AVE','','JENNIFER CARTER','BARBARA CARTER' UNION ALL SELECT 2,'2168 MAIN ST','HNGR F','DANIEL HERNANDEZ','SUSAN MARTIN' // etc another 98 times... // FYI, this is not real data! I'm building this INSERT script in batches of 100. It's taking on average 175 ms to run each insert. Does this seem like a long time? It's going to take about 35 mins to run the whole insert. The table doesn't have a primary key or any indexes. I was planning on adding those after all the data in inserted (thinking that that would be faster). Is there a better way to do this?

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  • Why should I use Entity Framework over Linq2SQL ...

    - by Refracted Paladin
    To be clear, I am not asking for a side by side comparision which has already been asked Ad Nauseum here on SO. I am also Not asking if Linq2Sql is dead as I don't care. What I am asking is this.... I am building internal apps only for a non-profit organization. I am the only developer on staff. We ALWAYS use SQL Server as our Database backend. I design and build the Databases as well. I have used L2S successfully a couple of times already. Taking all this into consideration can someone offer me a compelling reason to use EF instead of L2S? I was at Code Camp this weekend and after an hour long demonstration on EF, all of which I could have done in L2S, I asked this same question. The speakers answer was, "L2S is dead..." Very well then! NOT! (see here) I understand EF is what MS WANTS us to use in the future(see here) and that it offers many more customization options. What I can't figure out is if any of that should, or does, matter for me in this environment. One particular issue we have here is that I inherited the Core App which was built on 4 different SQL Data bases. L2S has great difficulty with this but when I asked the aforementioned speaker if EF would help me in this regard he said "No!"

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  • C# HTML tags inside GridView

    - by Geo Ego
    I have a SharePoint web part that I wrote in C# which is used to display SQL Server data based on user selections. I pull the data with a DataReader, fill a DataSet with it, and set that DataSet as the DataSource in a GridView and add that control to my page. The only problem I'm facing is that line breaks in the data fields are not being rendered at all. I'm simply getting a block of text that ignores the breaks that are present in the database when it's rendered to HTML. I tried a regex: Regex rgx = new Regex("\n"); string inputStr = Convert.ToString(dr[x]); string outputStr = rgx.Replace(inputStr, "<br />"); newRow[ds3.Tables["Bobst Specs 3"].Columns[x]] = outputStr; While that does detect and replace the newlines, I merely get the text "" with no line breaks. I also tried changing my SQL query to something along the lines of: SELECT REPLACE (fldCustomerName, '. ', '.' + @NewLineChar) This apparently renders more newlines. I can see that they are present, because if I also insert the regex they are affected, but do not create line breaks. I'm not sure how to replace these, and what with, to get the lines to actually break.

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  • Updating MS Access Database from Datagridview

    - by Peter Roche
    I am trying to update an ms access database from a datagridview. The datagridview is populated on a button click and the database is updated when any cell is modified. The code example I have been using populates on form load and uses the cellendedit event. private OleDbConnection connection = null; private OleDbDataAdapter dataadapter = null; private DataSet ds = null; private void Form2_Load(object sender, EventArgs e) { string connetionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='C:\\Users\\Peter\\Documents\\Visual Studio 2010\\Projects\\StockIT\\StockIT\\bin\\Debug\\StockManagement.accdb';Persist Security Info=True;Jet OLEDB:Database Password="; string sql = "SELECT * FROM StockCount"; connection = new OleDbConnection(connetionString); dataadapter = new OleDbDataAdapter(sql, connection); ds = new DataSet(); connection.Open(); dataadapter.Fill(ds, "Stock"); connection.Close(); dataGridView1.DataSource = ds; dataGridView1.DataMember = "Stock"; } private void addUpadateButton_Click(object sender, EventArgs e) { } private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e) { try { dataadapter.Update(ds,"Stock"); } catch (Exception exceptionObj) { MessageBox.Show(exceptionObj.Message.ToString()); } } The error I receive is Update requires a valid UpdateCommand when passed DataRow collection with modified rows. I'm not sure where this command needs to go and how to reference the cell to update the value in the database.

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  • Select * from 'many to many' SQL relationship

    - by Rampant Creative Group
    I'm still learning SQL and my brain is having a hard time with this one. Say I have 3 tables: teams players and teams_players as my link table All I want to do is run a query to get each team and the players on them. I tried this: SELECT * FROM teams INNER JOIN teams_players ON teams.id = teams_players.team_id INNER JOIN players ON teams_players.player_id = players.id But it returned a separate row for each player on each team. Is JOIN the right way to do it or should I be doing something else? ----------------------------------------- Edit Ok, so from what I'm hearing, this isn't necessarily a bad way to do it. I'll just have to group the data by team while I'm doing my loop. I have not yet tried the modified SQL statements provided, but I will today and get back to you. To answer the question about structure - I guess I wasn't thinking about the returned row structure which is part of what lead to my confusion. In this particular case, each team is limited to 4 players (or less) so I guess the structure that would be helpful to me is something like the following: teams.id, teams.name, players.id, players.name, players.id, players.name, players.id, players.name, players.id, players.name, 1 Team ABC 1 Jim 2 Bob 3 Ned 4 Roy 2 Team XYZ 2 Bob 3 Ned 5 Ralph 6 Tom

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  • Connecting to MS SQL Server 2005 via Web Service

    - by clear-cycle-corp
    Delphi 2010, dbExpress, and MS SQL Server 2005 DB Ok, I am trying to make a connection to a MS SQL 2005 DB using Delphi 2010 & DBExpress. If I create a standard delphi application and hard code my connection (IT WORKS!): procedure TForm1.Button1Click(Sender: TObject); var Conn: TSQLConnection; begin Conn:= TSQLConnection.Create(nil); Conn.ConnectionName:= 'VPUCDS_VPN_SE01'; Conn.LoadParamsOnConnect := True; Conn.LoginPrompt:=True; try Conn.Connected:= True; if Conn.Connected then ShowMessage('Connected!') else ShowMessage('NOT Connected!') finally Conn.Free; end; end; All the ini files, and DLLs reside in the same folder as my executable and yes, I have DBXMsSQL & MidasLib in the uses clause again, it works if its not a web service! However, if i then move the code over to a Web serices CGI module: function TTest.ConnectToDB: Boolean;stdcall; var Conn: TSQLConnection; begin Conn:= TSQLConnection.Create(nil); Conn.ConnectionName:= 'VPUCDS_VPN_SE01'; Conn.LoadParamsOnConnect := True; Conn.LoginPrompt:=True; try Conn.Connected:= True; result:= Conn.Connected; finally Conn.Free; end; end; Thanks

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  • Optimal two variable linear regression calculation

    - by Dave Jarvis
    Problem Am looking to apply the y = mx + b equation (where m is SLOPE, b is INTERCEPT) to a data set, which is retrieved as shown in the SQL code. The values from the (MySQL) query are: SLOPE = 0.0276653965651912 INTERCEPT = -57.2338357550468 SQL Code SELECT ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT, FROM (SELECT D.AMOUNT, Y.YEAR FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 8590 AND -- Find all the stations within a 15 unit radius ... -- SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < 15 AND -- Gather all known years for that station ... -- S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND -- The data before 1900 is shaky; insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '001' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ORDER BY Y.YEAR ) t Data The data is visualized here: Question The following results (to calculate the start and end points of the line) appear incorrect. Why are the results off by ~10 degrees (e.g., outliers skewing the data)? (1900 * 0.0276653965651912) + (-57.2338357550468) = -4.66958228 (2009 * 0.0276653965651912) + (-57.2338357550468) = -1.65405406 I would have expected the 1900 result to be around 10 (not -4.67) and the 2009 result to be around 11.50 (not -1.65). Related Sites Least absolute deviations Robust regression Thank you!

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  • How can I check if a user has written his username and password correctly?

    - by Sergio Tapia
    I'm using a Linq-to-SQL class called Scans.dbml. In that class I've dragged a table called Users (username, password, role) onto the graphic area and now I can access User object via a UserRepository class: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Scanner.Classes { public class UserRepository { private ScansDataContext db = new ScansDataContext(); public User getUser(string username) { return db.Users.SingleOrDefault(x => x.username == username); } public bool exists(string username) { } } } Now in my Login form, I want to use this Linq-to-SQL goodness to do all the data related activities. UserRepository users = new UserRepository(); private void btnLogin_Click(object sender, EventArgs e) { loginToSystem(); } private void loginToSystem() { if (users.getUser(txtUsername.Text)) { } //If txtUsername exists && User.password == Salt(txtPassword) //then Show.MainForm() with User.accountType in constructor to set permissions. } I need help with verifying that a user exists && that that users.password is equal to SALT(txtpassword.text). Any guidance please?

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  • Visual C++ 2008 runtime error-- debug vs release exe problem?

    - by larryq
    Hi everyone, I have a Windows executable (native, not .Net) project that I'm trying to pass along to a new team member. It's a graphics modeling tool that uses the Qt widget library and OpenGL. The project runs fine on my box but when we buld and link it on this new member's machine and he tries deubugging it, here's what he sees (not all entries included, for brevity): ModelingTool.exe': Loaded 'C:\ModelingTool\ModelingTool\ModelingTool\Debug\ModelingTool.exe', Symbols loaded. 'ModelingTool.exe': Loaded 'C:\Windows\System32\ntdll.dll', Cannot find or open the PDB file 'ModelingTool.exe': Loaded 'C:\Windows\System32\kernel32.dll', Cannot find or open the PDB file 'ModelingTool.exe': Loaded 'C:\Windows\System32\opengl32.dll', Cannot find or open the PDB file 'ModelingTool.exe': Loaded 'C:\Windows\System32\msvcrt.dll', Cannot find or open the PDB file 'ModelingTool.exe': Loaded 'C:\Windows\System32\dwmapi.dll', Cannot find or open the PDB file 'ModelingTool.exe': Loaded 'C:\Qt\4.2.2\bin\Qt3Supportd4.dll', Symbols loaded. 'ModelingTool.exe': Loaded 'C:\Program Files\Spyware Doctor\smum32.dll', Binary was not built with debug information. Debugger:: An unhandled non-continuable exception was thrown during process load The program '[5936] ModelingTool.exe: Native' has exited with code -1072365566 (0xc0150002). Would anyone care to guess what's wrong here? Some sort of debug-release mismatch perhaps?

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  • Linking Listbox child categories

    - by Gerardo Abdo
    Hello I have few monhts working with aspx, and now I'm developing a shopping cart website. For the employee to upload the products on the DB, every product needs to be linked to a category and sub category, and sub-sub category, and so on. Sometimes the sub-sub categories are up to 5. For example Electronics-TV-LCD-Samsung-40 inches. First, What I would like to identify is if the SQL table has the apporpiate structure. I have 3 columns Id, Description, Parent_Id. Categories with Parent Id=0 is used for the top ones. Is this the best way to do it? Then I want to use the ListBox control to select main Categories, and once it is selected, filled a second listbox with its childs and so on. Do I need to query SQL DB everytime the change event happens? I heard about linq but have not used yet, What would be your suggestion to do this. If you have seen a sample to understand it better will be appreciated. Thank you

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  • Generating MySQL UPDATE statements containing BLOB image data

    - by Bob
    I'm trying to write an SQL statement that will generate an SQL script that will update a BLOB field with an IMAGE being selected from the database. This is what I have: select concat( 'UPDATE `IMAGE` SET THUMBNAIL = ', QUOTE( THUMBNAIL ), ' WHERE ID = ', ID, ';' ) as UPDATE_STATEMENT from IMAGE; In the above, THUMBNAIL is a BLOB field containing raw image data. When I run the resulting script I get the following error: ERROR at line 2: Unknown command '\\'. I first tried this without the QUOTE() function, like so: select concat( 'UPDATE `IMAGE` SET THUMBNAIL = \'', THUMBNAIL, '\' WHERE ID = ', ID, ';' ) as UPDATE_STATEMENT from IMAGE; Running the resulting script produces this error: ERROR at line 2: Unknown command '\0'. What is the proper function to apply to this BLOB field in the select, so the UPDATE statements will work? If context is required, I'm looking to migrate thumbnails generated on one server to another server for certain image IDs only. I would use mysqldump, but I don't want to clobber the entire table. Any help is greatly appreciated!

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  • Get a "sqlceqp35.dll" error when debugging but not when running deployed code.

    - by nj
    In our current windows mobile project a problem while debugging recently arised. When trying to debug the code it throws an exception on the open command on a connection to the local database. The message is "A SQL Server Compact DLL could not be loaded. Reinstall SQL Server Compact Edition. [ DLL Name = sqlceqp35.dll ]". Sometime it's an unknow error instead, with reference to the same file. If you execute the binary, thats deployd during the debug, on the device it runs without any problem. I've tried: Reinstall both .net and sqlce on the device. Changed the "specific version" on the reference properties in the project. The hardware I'm using is a Motorola MC70 with Windows mobile 5.0. The target platform of the project is windows mobile 5.0. Any ideas on what might cause this problem? EDIT: When I tried it on a MC75 I can debug it. The MC70 got OS Version: 05.01.0478 and the MC75 05.01.0478. My best guess now is that it's someway related to the OS version or the actual device.

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  • IF expression in SQL

    - by chupinette
    INSERT INTO item_quotation (item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) SELECT DISTINCT I.item_id," . $quotation_id . ",T.item_name, I.name,I.other_name, INV.selling_price, I.discounted_price FROM temp_quotations T, item I, inventory INV<br/> WHERE ( I.name LIKE CONCAT( '%', T.item_name, '%' ) OR I.other_name LIKE CONCAT( '%', T.item_name, '%' )) AND INV.item_id = I.item_id; I have a table called temp_quotations(temp_item_id,item_name)having values (1,grinder), (2,drill), (3,kit) I have another table called item(item_id,name,other_name,discounted_price) having values (1,grinder A,100),(2,kit A,200) When I execute this sql, it insert values in table item_quotation(item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) for example in this case it will insert (1,1,grinder,grinder A,150,100) (2,1,kit,kit A, 250,200) Since the item drill is not found in table item, it wont display it in table item_quotations. I want to write an if statement within that sql so that when the item_name from temp_quotation does not match the name from item, it displays not found in the place of item_name. This is what i tried but it does not display "not found": INSERT INTO item_quotation (item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) SELECT DISTINCT I.item_id," . $quotation_id . ",T.item_name, IF(I.name LIKE CONCAT( '%', T.item_name, '%' ),I.name,'not found'),I.other_name, INV.selling_price, I.discounted_price FROM temp_quotations T, item I, inventory INV WHERE ( I.name LIKE CONCAT( '%', T.item_name, '%' ) OR I.other_name LIKE CONCAT( '%', T.item_name, '%' )) AND INV.item_id = I.item_id;

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  • Bidirectional replication update record problem

    - by Mirek
    Hi, I would like to present you my problem related to SQL Server 2005 bidirectional replication. What do I need? My teamleader wants to solve one of our problems using bidirectional replication between two databases, each used by different application. One application creates records in table A, changes should replicate to second database into a copy of table A. When data on second server are changed, then those changes have to be propagated back to the first server. I am trying to achieve bidirectional transactional replication between two databases on one server, which is running SQL Server 2005. I have manage to set this up using scripts, established 2 publications and 2 read only subscriptions with loopback detection. Distributtion database is created, publishment on both databases is enabled. Distributor and publisher are up. We are using some rules to control, which records will be replicated, so we need to call our custom stored procedures during replication. So, articles are set to use update, insert and delete custom stored procedures. So far so good, but? Everything works fine, changes are replicating, until updates are done on both tables simultaneously or before changes are replicated (and that takes about 3-6 seconds). Both records then end up with different values. UPDATE db1.dbo.TestTable SET Col = 4 WHERE ID = 1 UPDATE db2.dbo.TestTable SET Col = 5 WHERE ID = 1 results to: db1.dbo.TestTable COL = 5 db2.dbo.TestTable COL = 4 But we want to have last change winning replication. Please, is there a way to solve my problem? How can I ensure same values in both records? Or is there easier solution than this kind of replication? I can provide sample replication script which I am using. I am looking forward for you ideas, Mirek

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  • Why use Entity Framework over Linq2SQL ...

    - by Refracted Paladin
    To be clear, I am not asking for a side by side comparision which has already been asked Ad Nauseum here on SO. I am also Not asking if Linq2Sql is dead as I don't care. What I am asking is this.... I am building internal apps only for a non-profit organization. I am the only developer on staff. We ALWAYS use SQL Server as our Database backend. I design and build the Databases as well. I have used L2S successfully a couple of times already. Taking all this into consideration can someone offer me a compelling reason to use EF instead of L2S? I was at Code Camp this weekend and after an hour long demonstration on EF, all of which I could have done in L2S, I asked this same question. The speakers answer was, "L2S is dead..." Very well then! NOT! (see here) I understand EF is what MS WANTS us to use in the future(see here) and that it offers many more customization options. What I can't figure out is if any of that should, or does, matter for me in this environment. One particular issue we have here is that I inherited the Core App which was built on 4 different SQL Data bases. L2S has great difficulty with this but when I asked the aforementioned speaker if EF would help me in this regard he said "No!"

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  • Way to get VS 2008 to stop forcing indentation on namespaces?

    - by Earlz
    I've never really been a big fan of the way most editors handle namespaces. They always force you to add an extra pointless level of indentation. For instance, I have a lot of code in a page that I would much rather prefer formatted as namespace mycode{ class myclass{ void function(){ foo(); } void foo(){ bar(); } void bar(){ //code.. } } } and not something like namespace mycode{ class myclass{ void function(){ foo(); } void foo(){ bar(); } void bar(){ //code.. } } } Honestly, I don't really even like the class thing being indented most of the time because I usually only have 1 class per file. And it doesn't look as bad here, but when you get a ton of code and lot of scopes, you can easily have indentation that forces you off the screen, and plus here I just used 2-space tabs and not 4-space as is used by us. Anyway, is there some way to get Visual Studio to stop trying to indent namespaces for me like that?

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  • .net IHTTPHandler Streaming SQL Binary Data

    - by Yisman
    Hello everybody I am trying to implement an ihttphandeler for streaming files. files may be tiny thumbnails or gigantic movies the binaries r stored in sql server i looked at a lot of code online but something does not make sense isnt streaming supposed to read the data piece by piece and move it over the line? most of the code seems to first read the whole field from mssql to memory and then use streaming for the output writing wouldnt it b more eficient to actually stream from disk directly to http byte by byte (or buffered chunks?) heres my code so far but cant figure out the correct combination of the sqlreader mode and the stream object and the writing system Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest context.Response.BufferOutput = False Dim FileField=safeparam(context.Request.QueryString("FileField")) Dim FileTable=safeparam(context.Request.QueryString("FileTable")) Dim KeyField=safeparam(context.Request.QueryString("KeyField")) Dim FileKey=safeparam(context.Request.QueryString("FileKey")) Using connection As New SqlConnection(ConfigurationManager.ConnectionStrings("Main").ConnectionString) Using command As New SqlCommand("SELECT " & FileField & "Bytes," & FileField & "Type FROM " & FileTable & " WHERE " & KeyField & "=" & FileKey, connection) command.CommandType = Data.CommandType.Text enbd using end using end sub please be aware that this sql command also returns the file extension (pdf,jpg,doc...) in the second field of the query thank you all very much

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  • ASP.NET 4.0 , SQL 2008 Web development and deployment Cloud or Shared Hosting?

    - by Tom
    Just to give you a fair idea, I am new to the web development / hosting world and planning to develop a Multilingual Social networking Web Applications in ASP.NET 4.0 , expected the content to deliver in many countries German, France, China, India and MiddleEast. My question is will Cloud Hosting provides a development environment? or should i buy software and develop in my system?. Which is the best hosting model for my scenario. I do know there will not be many users and expecting a steady growth. Tom

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  • How to pass a Dictionary variable to another procedure

    - by salvationishere
    I am developing a C# VS2008/SQL Server website application. I've never used the Dictionary class before, but I am trying to replace my Hashtable with a Dictionary variable. Here is a portion of my aspx.cs code: ... Dictionary<string, string> openWith = new Dictionary<string, string>(); for (int col = 0; col < headers.Length; col++) { @temp = (col + 1); @tempS = @temp.ToString(); @tempT = "@col" + @temp.ToString(); ... openWith.Add(@tempT, headers[col]); } ... for (int r = 0; r < myInputFile.Rows.Count; r++) { resultLabel.Text = ADONET_methods.AppendDataCT(myInputFile, openWith); } But this is giving me a compiler error on this last line: Argument '2': cannot convert from 'System.Collections.Generic.Dictionary' to 'string' How do I pass the entire openWith variable to AppendDataCT? AppendDataCT is the method that calls my SQL stored proc. I want to pass in the whole row where each row has a unique set of values that I want to add to my database table. For example, if each row requires values for cells A, B, and C, then I want to pass these 3 values to AppendDataCT, where all of these values are strings. How do I do this with Dictionary?

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  • LinqToSql Select to a class then do more queries

    - by fyjham
    I have a LINQ query running with multiple joins and I want to pass it around as an IQueryable<T> and apply additional filters in other methods. The problem is that I can't work out how to pass around a var data type and keep it strongly typed, and if I try to put it in my own class (EG: .Select((a,b) => new MyClass(a,b))) I get errors when I try to add later Where clauses because my class has no translations into SQL. Is there any way I can do one of the following: Make my class map to SQL? Make the var data-type implement an interface (So I can pass it round as though it's that)? Something I haven't though of that'll solve my issue? Example: public void Main() { using (DBDataContext context = new DBDataContext()) { var result = context.TableAs.Join( context.TableBs, a => a.BID, b => b.ID, (a,b) => new {A = a, B = b} ); result = addNeedValue(result, 4); } } private ???? addNeedValue(???? result, int value) { return result.Where(r => r.A.Value == value); } PS: I know in my example I can flatten out the function easily, but in the real thing it'd be an absolute mess if I tried.

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  • Need some help with a MySQL subquery count

    - by Ferdy
    I'm running into my own limits of MySQL query skills, so I hope some SQL guru can help out on this one. The situation is as follow: I have images that can be tagged. As you might expect this is stored in three tables: Image Tag Tag_map (maps images to tags) I have a SQL query that calculates the related tags based on a tag id. The query basically checks what other tags were used for images for images using that tag. Example: Image1 tagged as "Bear" Image2 tagged as "Bear" and "Canada" If I throw "Bear" (or its tag id) at the query, it will return "Canada". This works fine. Here's the query: SELECT tag.name, tag.id, COUNT(tag_map.id) as cnt FROM tag_map,tag WHERE tag_map.tag_id = tag.id AND tag.id != '185' AND tag_map.image_id IN (SELECT tag_map.image_id FROM tag_map INNER JOIN tag ON tag_map.tag_id = tag.id WHERE tag.id = '185') GROUP BY tag_map.id LIMIT 0,100 The part I'm stuck with is the count. For each related tag returned, I want to know how many images are in that tag. Currently it always returns 1, even if there are for example 3. I've tried counting different columns all resulting in the same output, so I guess there is a flaw in my thinking.

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  • How do I simulate "In" using Linq2Sql

    - by flipdoubt
    I often find myself with a list of disconnected Linq2Sql objects or keys that I need to re-select from a Linq2Sql data-context to update or delete in the database. If this were SQL, I would use IN in the SQL WHERE clause, but I am stuck with what to do in Linq2Sql. Here is a sample of what I would like to write: public void MarkValidated(IList<int> idsToValidate) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate).ToList(); foreach(var item in items) item.Validated = DateTime.Now; _Db.SubmitChanges(); } // Disposes of DataContext } Or: public void DeleteItems(IList<int> idsToDelete) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate); _Db.Items.DeleteAllOnSubmit(items); _Db.SubmitChanges(); } // Disposes of DataContext } Can I get this done in one trip to the database? If so, how? Is it possible to send all those ints to the database as a list of parameters and is that more efficient than doing a foreach over the list to select each item one at a time?

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • A many-to-many relation joined disallows intellisense/lookup in joined table

    - by BerggreenDK
    I want to be able to select a product and retrieve all sub-parts(products) within it. My approach is to find the Product id and then retrieve the list of ProductParts with that as a parent and while fetching those, follow the key back to the Product child to get the name and details of each Part. I was hoping to use something similar to: part.linked_product_id.name I have two tables. One for [Product] and and a relation [ProductPart] that has two FK ID's to [Product] Table Product() { int ID; // (PRIMARY, NOT NULL) String Name; ... details removed for overview purpose... } Table ProductPart() { int Product_ID; // FK (linked with relation to Product/parent) int Part_Product_ID; // FK (linked with relation to Product/childen) ... details removed for overview purpose... } I have checked the SQL-diagram and it shows the two relations (both are one to many) and in my DBML they also looks right. Here is my LINQ to SQL snippet that doesnt work for me... wondering why my joins dont work as supposed. FaultySnippet() { ProductDataContext db = new ProductDataContext(); var list = ( from part in db.ProductParts join prod in db.Products on part.Part_Product_ID equals prod.ID where (part.Product_ID == product_ID) select new { Name = part.Part_Product_ID. ?? // <-- NO details from Joined table? ... rest of properties from ProductPart join... I hoped... } ); }

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  • What is a good way to assign order #s to ordered rows in a table in Sybase

    - by DVK
    I have a table T (structure below) which initially contains all-NULL values in an integer order column: col1 varchar(30), col2 varchar(30), order int NULL I also have a way to order the "colN" columns, e.g. SELECT * FROM T ORDER BY some_expression_involving_col1_and_col2 What's the best way to assign - IN SQL - numeric order values 1-N to the order table, so that the order values match the order of rows returned by the above ORDER BY? In other words, I would like a single query (Sybase SQL syntax so no Oracle's rowcount) which assigns order values so that SELECT * FROM T ORDER BY order returns 100% same order of rows as the query above. The query does NOT necessarily need to update the table T in place, I'm OK with creating a copy of the table T2 if that'll make the query simpler. NOTE1: A solution must be real query or a set of queries, not involving a loop or a cursor. NOTE2: Assume that the data is uniquely orderable according to the order by above - no need to worry about situation when 2 rows can be assigned the same order at random. NOTE3: I would prefer a generic solution, but if you wish a specific example of ordering expression, let's say: SELECT * FROM T ORDER BY CASE WHEN col1="" THEN "AAAAAA" ELSE col1 END, ISNULL(col2, "ZZZ")

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