Sql - Dynamically Varied Number Of Conditions In The 'where' Statement Using LINQ?

Feb 3, 2010

I'm working on my first project using LINQ (in mvc), so there is probably something very simple that I missed. However, a day of searching and experimenting has not turned up anything that works, hence the post.

I'm trying to write a LINQ query (Linq to SQL) that will contain a multiple number of conditions in the where statement separated by an OR or an AND. We don't know how many conditions are going to be in the query until runtime. This is for a search filter control, where the user can select multiple criteria to filter by.

select * from table
where table.col = 1
OR table.col = 2
OR table.col = 7
'number of other conditions

Before I would just construct the SQL query as a string while looping over all conditions. However, it seems like there should be a nice way of doing this in LINQ. I have tried looking using expression trees, but they seem a bit over my head for the moment. Another idea was to execute a lambda function inside the where statement, like so:

For Each value In values matchingRows = matchingRows.Where(Function(row) row.col = value)However, this only works for AND conditions. How do I do ORs?

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the testBoolean is set to the value True, but for some reason when debugging, it step through both conditions, so in the end the button1.visble becomes False, but I want it to be set to True.[code]....

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Dec 9, 2011

So I am trying to evaluate 3 conditions in an if statement. Its not working how I would assume it should. I basically want to do this:

vb.net
If PGN = &HEF007E And PGNData(0) = &H58 And (PGNData(1) And &H40) = &H40 Then IgnOn = True Else IgnOn = False

If I write it in that manner it gives inconsistent results. If I workaround by writing it this way it works perfectly:

vb.net
If PGN = &HEF007E And PGNData(0) = &H58 Then
If (PGNData(1) And &H40) = &H40 Then IgnOn = True Else IgnOn = False
Endif

What is the proper way to do this with only one if statement?

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I currently have an If...Then statement that checks if all fields of a form have been filled before saving the info in a file. I'd like to be able to tell which field has not been filled to give the user a dynamic message (at the moment, it only tells them that the checklist is not completed ) :

If (txtNoDemande.TextLength = 8 _
Or txtNoDemande.TextLength = 13 _
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[CODE]...

Is there a way to determine which of these conditions is false without having to do a seperate If statement for each ?

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Feb 27, 2010

I am trying to write a Function which will return a data table, filled with a data from a database.

The Function will accept 6 diffrenet parameters as Optional. Each one of them will be an additional condition to be added to a where clause, if it`s provided when the function is beeing called.

Is there any method in .NET to simply add a new condition to the where clause?

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Jul 8, 2010

How would I perform this SQL query

Select Distinct s.*
from #ScopeIDs x
Join Scopes s on s.ScopeID=x.ScopeID or x.ScopeID is null

in LINQ to SQL? (This query would return all Scopes whose ScopeID is present in #ScopeIDs, unless one of the entries in #ScopeIDs is null, in which case it returns all Scopes).

A "literal" translation doesn't work, since LINQ doesn't support joining with multiple conditions - code along these lines ...

From x in ScopeIDs
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Jan 16, 2012

I have the following:

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Registration Date (c.AppliedDate)

Is it possible to all of this in LINQ?

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Mar 22, 2011

I have a form that contains multiple conditional or if statements on several defferent for controls.

Example: Radio Buttons, TextBoxes and CheckBoxes.

I am intending to create an order form(demo) where the user can select multiple products.

I have a default order number that changes by one everytime an order is successful.

An order is only successful if all the information on the form is entered correctly.

My question is where do I insert the code for the order number?

Basically for the order number I have a counter that count by increment of one if an order is successful.

Meaning when the user hit place order, and all the infromation is right, then the order numer goes to 1 from zero.

Where do I add the condition for the order number since all the fields must first be completed.

Do I have to create a whole line of if else statements?

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I have the following SQL:

[Code]...

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Oct 20, 2011

This may be simple, but im having a tough go at it. I'm trying to make a "review" section in a step through form, where the user can see everything that has been entered and if they choose go back and "edit" that information again. One section only has to show the information that has been added by the user, basically if they don't select a certain checkbox there is no reason to display the info for that box.I want to to dynamically create labels in a Panel (Panel7) on a TabPage (TabPage3), only for the checkbox information that was selected. This is what I have right now, and I am unable to see anything on the page, I have also tried without the panel and straight onto the tabpage itself to no avail.

MsgBox(CurPat, MsgBoxStyle.Critical)
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Dim lblTemp As New Label

[code].....

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Jan 29, 2010

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Dim Data = From c In aw.TestDatabase_TestTable _
Select c.No, c.Description
DataGridView1.DataSource = Data
End Using

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Dim query = _
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[Code]....

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Current code:

If hour = 8 And min = 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 or 32 or 33 or 34 or 35 or 36 or 37 or 38 or 39 or 40 Then
TextBox1.Text = "Test"
Else
TextBox1.Text = "Text1"
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Where((this = 1 AND that = 2) OR (this = 1 AND that = 4) OR (this = 2 AND that = 4))

but the problem is the number will have to be determined dynamically at runtime, and added using a loop, like

for each item in myItems
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next

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Ok im trying to do a if statement in Linq and was wondering if it was possible to do something like:

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[Code]...

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Aug 13, 2009

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Mar 28, 2012

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Public Class Customer
Public Overridable Property ContactNumbers As List(Of ContactNumber)
End Class

[Code].....

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Feb 17, 2011

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EDIT

So Both of the answers seem to be saying the same general Idea. I'm going to try to convert the C# into VB and get it to work.

The first answer converts to

NotInheritable Class DataContextExtensions
Private Sub New()
End Sub

[Code].....

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[code].....

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Jun 16, 2011

I have something that I want to do and what looks very simple, but I cannot get it to work. I want to build a function that gets as input a xdocument and some other strings. It should have a return that contains a filtered part of the xdocument in a way that I can use it as input for a new Linq function. This is what I mean:

Private Function fncGetFilteredDecendantsOfNode(ByVal xdocDoc As XDocument, _

[Code]...

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How can I turn the following query into a LINQ statement? [code]

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May 18, 2012

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Dim Variable1 as string=Biology
Dim Variable2 as string=Chemistry
Dim Variable3 as string=English

[code].....

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Oct 15, 2010

We use LINQ to SQL extensively, and one of the biggest performance pitfalls we've run into is situations where a query can't be converted to SQL, and so an entire database table gets loaded into memory and the query performed by .NET. For example, this query

Dim Foo = (From c in Db.Contacts Select c Where c.ContactID=MyContactID)
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Dec 14, 2009

I have this LINQ statement [code]...

Is there any way that I can use if/iif within select ?

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