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  • A linq join combined with a regex

    - by Geert Beckx
    Is it possible to combine these 2 queries or would this make my code too complex? Also I think there should be a performance gain by combining these queries since I think in the near future my source table could be over 11000 records. This is what i came up with so far : Dim lit As LiteralControl ' check characters not in alphabet Dim r As New Regex("^[^a-zA-Z]+") Dim query = From o In source.ToTable _ Where r.IsMatch(o.Field(Of String)("nam")) lit = New LiteralControl(String.Format("letter: {0}, count: {1}<br />", "0-9", query.Count)) plhAlpabetLinks.Controls.Add(lit) Dim q = From l In "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToLower.ToCharArray _ Group Join o In source.ToTable _ On l Equals o.Field(Of String)("nam").ToLowerInvariant(0) Into g = Group _ Select l, g.Count ' iterate the alphabet to generate all the links. For Each letter In q.AsEnumerable lit = New LiteralControl(String.Format("letter: {0}, count: {1}<br />", letter.l, letter.Count)) plhAlpabetLinks.Controls.Add(lit) Next Kind regards, G.

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  • DataTable linq query iteration

    - by Ravi
    Hi, I want to Enumerate Linq Query. Below i specified example. EX: DataTable _slidingDataTable = new DataTable("test"); for(int i=0; i<5;i++) { DataRow row = _slidingDataTable.NewRow(); startPosition = DateTime.Now; for(int i=0; i<5;i++) { _slidingDataTable.Columns.Add("TransferTime"); row[columnName] = startPosition ; _slidingDataTable.Columns.Add("TransferData"); row[columnName] = "Test"+i; } _slidingDataTable.Rows.Add(row); } var query1 = from myRow in _slidingDataTable.AsEnumerable() where myRow.Field<DateTime>("TransferTime") == startPosition select myRow; This query output should be collection of rows. How to get collection row & iterate.

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  • c# creating a database query METHOD

    - by Sinaesthetic
    I'm not sure if im delluded but what I would like to do is create a method that will return the results of a query, so that i can reuse the connection code. As i understand it, a query returns an object but how do i pass that object back? I want to send the query into the method as a string argument, and have it return the results so that I can use them. Here's what i have which was a stab in the dark, it obviously doesn't work. This example is me trying to populate a listbox with the results of a query; the sheet name is Employees and the field/column is name. The error i get is "Complex DataBinding accepts as a data source either an IList or an IListSource.". any ideas? public Form1() { InitializeComponent(); openFileDialog1.ShowDialog(); openedFile = openFileDialog1.FileName; lbxEmployeeNames.DataSource = Query("Select [name] FROM [Employees$]"); } public object Query(string sql) { System.Data.OleDb.OleDbConnection MyConnection; System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand(); string connectionPath; //build connection string connectionPath = "provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + openedFile + "';Extended Properties=Excel 8.0;"; MyConnection = new System.Data.OleDb.OleDbConnection(connectionPath); MyConnection.Open(); myCommand.Connection = MyConnection; myCommand.CommandText = sql; return myCommand.ExecuteNonQuery(); }

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  • C# LINQ join With Just One Row

    - by Soo
    I'm trying to make a query that grabs a single row from an SQL database and updates it. TableA AId AValue TableB BId AId BValue Ok, so TableA and TableB are linked by AId. I want to select a row in TableB based on AValue using a join. The following query is what I have and only grabs a value from TableB based on AId, I just don't know how to grab a row from TableB using AValue. I know you would need to use a join, but I'm not sure how to accomplish that. var row = DbObject.TableB.Single(x => x.AId == 1) row.BValue = 1; DbObject.SubmitChanges();

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  • Dynamic "WHERE IN" on IQueryable (linq to SQL)

    - by user320235
    I have a LINQ to SQL query returning rows from a table into an IQueryable object. IQueryable<MyClass> items = from table in DBContext.MyTable select new MyClass { ID = table.ID, Col1 = table.Col1, Col2 = table.Col2 } I then want to perform a SQL "WHERE ... IN ...." query on the results. This works fine using the following. (return results with id's ID1 ID2 or ID3) sQuery = "ID1,ID2,ID3"; string[] aSearch = sQuery.Split(','); items = items.Where(i => aSearch.Contains(i.ID)); What I would like to be able to do, is perform the same operation, but not have to specify the i.ID part. So if I have the string of the field name I want to apply the "WHERE IN" clause to, how can I use this in the .Contains() method?

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  • Grouping by property value and writing group members

    - by Will S
    I need to group the following list by the department value but am having trouble with the LINQ syntax. Here's my list of objects: var people = new List<Person> { new Person { name = "John", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Sally", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Bob", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, new Person { name = "Wanda", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, }; I've toyed around with grouping. This is as far as I've got: var query = from p in people from field in p.department where field.name == "department" group p by field.value into departments select new { Department = departments.Key, Name = departments }; So can iterate over the groups, but not sure how to list the Person names - foreach (var department in query) { Console.WriteLine("Department: {0}", department.Department); foreach (var foo in department.Department) { // ?? } } Any ideas on what to do better or how to list the names of the relevant departments?

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  • where clause in linq query

    - by masoud
    in the below code "transmittalno.TransID" always has value but "doctranstocon.Transid" sometimes has value and sometimes does not, so when "doctranstocon.Transid" has value I have no problem but when there is not any value, when compare in the where clause like :"transmittalno.TransID == doctranstocon.Transid". It returns error" Object reference not set to an instance of an object." TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon I like TranstoCons returns null when there is not any value for " doctranstocon.Transid " How I can handle this error in the below linq query: var query = from transmittalno in _Transmittals Select new TransmittaltoConPresentationModel { TransID = transmittalno.TransID, Transmittal = transmittalno.TRANSMITTAL, TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon };

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  • Simple UPDATE query with (sometime) long query times

    - by Eric
    I run a dedicated MySQL server (2 cores, 16GB RAM) serving 100-200 requests per second. It is getting sluggish during peak traffic and I have a hard time optimizing the server. So I'm looking for some ideas now that I have done lots of Innodb fine-tuning with the "TUNING PRIMER" The query that now generates most slow queries is the following (see result from mysqldumpslow): Count: 433 Time=3.40s (1470s) Lock=0.00s (0s) Rows=0.0 (0), UPDATE user_sessions SET tid='S' WHERE idsession='S' I am very surprised to have so many long queries for such a simple query with no locking. Fyi, the table is InnoDB and has 14000 rows. It contains all active sessions on the site with approx 10 UPDATE and SELECT hits per second. Here is its structure: CREATE TABLE `user_sessions` ( `personid` mediumint(9) NOT NULL DEFAULT '0', `ip` varchar(18) COLLATE utf8_unicode_ci NOT NULL, `idsession` varchar(32) COLLATE utf8_unicode_ci NOT NULL, `datum` date NOT NULL DEFAULT '0000-00-00', `tid` time NOT NULL DEFAULT '00:00:00', `status` tinyint(4) NOT NULL DEFAULT '0', KEY `personid` (`personid`), KEY `idsession` (`idsession`), KEY `datum` (`datum`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci Any ideas?

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  • Linq, double left join and double count

    - by Fabian Vilers
    Hi! I'm looking to translate this SQL statement to a well working & performant LINQ command. I've managed to have the first count working using the grouping count and key members, but don't know how to get the second count. select main.title, count(details.id) as details, count(messages.id) as messages from main left outer join details on main.id = details.mainid left outer join messages on details.id = messages.detailid group by main.title Any advice is welcome! Fabian

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  • LINQ to SQL SOUNDEX - possible?

    - by Steve Hayes
    Hello, I have done a little bit of research on this and looked through a few articles both here on StackOverflow as well as some blog posts, but haven't found an exact answer. I also read that it is possible to do it using the 4.0 framework, but have yet to find any supporting evidence. So my question, is it possible to perform SOUNDEX via a LINQ to SQL Query?

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  • Concatenate int and string in LINQ

    - by Waheed
    HI, I am using the following code from c in Country where c.IsActive.Equals(true) orderby c.CountryName select new { countryIDCode = c.CountryID + "|" + c.TwoDigitCode, countryName = c.CountryName } but following is the error while doing this... Unable to cast the type 'System.Int32' to type 'System.Object'. LINQ to Entities only supports casting Entity Data Model primitive types. CountryID is int type and TwoDigitCode is string type. Can u please let me know how to concatenate.... Thanks....

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  • Is there Linq to Nhibernate for stateless session?

    - by Jenea
    I was using regular session for loading some items from database via linq. The problem is that it caches the entities and memory load increases very much unnecessarily. Is there a way to replace session with stateless session without introducing many changes in client code?

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  • Sorting an observable collection with linq

    - by zachary
    I have an observable collection and I sort it using linq. Everything is great, but the problem I have is how do I sort the actual observable collection? Instead I just end up with some IEnumerable thing and I end up clearing the collection and adding the stuff back in. This can't be good for performance. Does anyone know of a better way to do this?

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  • Linq to SQL - Invalid attempt to call FieldCount when reader is closed

    - by Justin
    Hey, Has anyone seen this error before when making a Linq to SQL call? Invalid attempt to call FieldCount when reader is closed Here's the code: public static MM GetDeviceConfiguration(long ipAddress) { string sprocName = ConfigurationBL.ReadSproc("ReadDeviceConfiguration"); return db.ExecuteQuery<MM>("exec {0} @IPAddressNumber = {1}", sprocName, ipAddress).FirstOrDefault(); } Thanks, Justin

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  • Encode double quotes inside XML element using LINQ to XML

    - by davekaro
    I'm parsing a string of XML into an XDocument that looks like this (using XDocument.Parse) <Root> <Item>Here is &quot;Some text&quot;</Item> </Root> Then I manipulate the XML a bit, and I want to send it back out as a string, just like it came in <Root> <Item>Here is &quot;Some text&quot;</Item> <NewItem>Another item</NewItem> </Root> However, what I am getting is <Root> <Item>Here is \"Some text\"</Item> <NewItem>Another item</NewItem> </Root> Notice how the double quotes are now escaped instead of encoded? This happens whether I use ToString(SaveOptions.DisableFormatting); or var stringWriter = new System.IO.StringWriter(); xDoc.Save(stringWriter, SaveOptions.DisableFormatting); var newXml = stringWriter.GetStringBuilder().ToString(); How can I have the double quotes come out as &quot; and not \"? UPDATE: Maybe this can explain it better: var origXml = "<Root><Item>Here is \"Some text&quot;</Item></Root>"; Console.WriteLine(origXml); var xmlDoc = System.Xml.Linq.XDocument.Parse(origXml); var modifiedXml = xmlDoc.ToString(System.Xml.Linq.SaveOptions.DisableFormatting); Console.WriteLine(modifiedXml); the output I get from this is: <Root><Item>Here is "Some text&quot;</Item></Root> <Root><Item>Here is "Some text"</Item></Root> I want the output to be: <Root><Item>Here is "Some text&quot;</Item></Root> <Root><Item>Here is "Some text&quot;</Item></Root>

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  • Help with Subsonic3 ActiveRecord LINQ query

    - by Saif Khan
    I have the following subsonic entities TInvoiceHeader TAccountAssociation How can I achieve the following in LINQ (subsonic) SELECT * from TInvoiceHeader WHERE custid IN (SELECT custid FROM TAccountAssociation WHERE username = 'a') I need to bind the results to a GridView.

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  • Help with Subsonic3 LINQ query

    - by Saif Khan
    I have the following subsonic entities TInvoiceHeader TAccountAssociation How can I achieve the following in LINQ SELECT * from TInvoiceHeader WHERE custid IN (SELECT custid FROM TAccountAssociation WHERE username = 'a') I need to bind the results to a GridView.

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  • asp.net update LINQ dbml files

    - by rockinthesixstring
    Is there a quick and easy way to update my LINQ dbml files? Right now, if I update a Stored Procedure, I need to open the dbml designer file, delete the old SP, save, drag and drop the new SP, and save again. I haven't researched this a whole bunch, but I'm wondering if there's an easy way for Visual Studio to just go into the DB and update the dbml to the latest SP's by just clicking an update button or something along those lines.

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  • Simple LINQ Aggregate Query

    - by Steven
    What is the vb.net equivalent of the following psuedo-code using LINQ? select min(credits) minCredits, max(credits) maxCredits, min(dollars) minDollars, max(dollars) maxDollars from players minCredits_lbl.Text = minCredits ... maxDollars_lbl.Text = maxDollars I have the following, but I can't figure out how to get any further. Dim query = From row in myDataSet.Tables("Players") _ Select credits = row("credits"), dollars = row("dollars")

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  • Linq find differences in two lists

    - by Salo
    I have two list of members like this: Before: Peter, Ken, Julia, Tom After: Peter, Robert, Julia, Tom As you can see, Ken is is out and Robert is in. What I want is to detect the changes. I want a list of what has changed in both lists. How can linq help me?

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  • Using Linq to filter a ComboBox.DataSource ?

    - by Pesche Helfer
    Hi board, in another topic, I've stumbled over this very elegant solution by Darin Dimitrov to filter the DataSource of one ComboBox with the selection of another ComboBox: how to filter combobox in combobox using c# combo2.DataSource = ((IEnumerable<string>)c.DataSource) .Where(x => x == (string)combo1.SelectedValue); I would like to do a similar thing, but intead of filtering by a second combobox, I would like to filter by the text of a TextBox. (Basically, instead of choosing from a second ComboBox, the user simply enters his filter in to a TextBox). However, it turned out to be not as straight forward as I had hoped it would be. I tried stuff as the following, but failed miserably: cbWohndresse.DataSource = ((IEnumerable<DataSet>)ds) .Where(x => x.Tables["Adresse"].Select("AdrLabel LIKE '%TEST%'")); cbWohndresse.DisplayMember = "Adresse.AdrLabel"; cbWohndresse.ValueMember = "Adresse.adress_id"; ds is the DataSet which I would like to use as filtered DataSource. "Adresse" is one DataTable in this DataSet. It contains a DataColumn "AdrLabel". Now I would like to display only those "AdrLabel", which contain the string from the user input. (Currently, %TEST% replaces the textbox.text.) The above code fails because the lambda expression does not return Bool. But I am sure, there are also other problems (which type should I use for IEnumerable? Now it's DataSet, but Darin used String. But how could I convert a DataSet to a string? Yes, I am as much newbyish as it gets, my experience is "void", and publicly so. So please forgive me my rather stupid questions. Your help is greatly appreciated, because I can't solve this on my own (tried hard already). Thank you very much! Pesche P.S. I am only using Linq to achieve an uncomplicated filter for the ComboBox (avoiding a View). The rest is not based on Linq, but on oldstyle Ado.NET (ds is filled by an SqlDataAdapter), if that's of any importance.

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  • LINQ weak relation between tables

    - by cleric
    I have two tables with a weak relation. I need get a text value from one table using a key from another. I am using the following C# LINQ code: City = rea.tRealEstateContact.tPostnumre != null ? rea.tRealEstateContact.tPostnumre.Bynavn : string.Empty But when the key cannot be found in the table 1(tPostnumre), an exception is thrown. How should I do this?

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