Convert LINQ Query Expression From C# To VB?
Mar 10, 2009I have the following C# LINQ query expression:
[code]...
how to convert this to VB.NET?
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Get The Count From A Query Expression In Linq?
Jan 25, 2012What I have right now is this:
Dim users = From users In tempTable _
Distinct Select users.Item("s_userid")
Dim usersCount As Integer = users.Count
But I pretty sure I shouldn't have to do that. I should be able to get the count in/from that first linq query.
Convert Linq.expression From C# To VB?
Mar 30, 2010[QueryInterceptor("Somethings")]
public Expression<Func<Something, bool>> OnSomethings()
{
// Code here
}
I had a view guesses, looked on msdn, but there are no examples matching the way that that is used.
C# - What Operators Should Have LINQ Query Expression Support
Oct 2, 2009Of the 51 Standard Query Operators (of which only 42 are actually query operators), only 24 are directly supported by Visual Basic 9 and just 11 by C# 3: Query Expression Syntax for Standard Query Operators.In many cases, query syntax is arguably more readable than the equivalent method syntax, especially when transparent identifiers are involved. However, that readability breaks down if you have to combine queries and method calls.So the question: What query operators, current or hypothetical, would you like to have your language of choice support in query expression syntax?
View 2 RepliesLinq Expression Chain Syntax For In Query?
Feb 25, 2011I have a query that I cannot seem to replicate in expression method chain syntax. I have two tables "User" and "UserPayment". User and UserPayment have a one to many relation i.e. One User can have many UserPayments.
View 1 RepliesHow To Convert SQL Query Into LINQ
Dec 8, 2011I am new to LINQ, how to convert the following SQL query to LINQ?
SELECT
Date,ShiftName,Max(Score) AS Score, 1 AS IsPreferred
FROM
Temp_Nurse_Fill_RequestNumbers
group by
ShiftName,date
How To Convert The SQL Query Into LINQ
Dec 8, 2011I am new to LINQ.convert the following SQL query to LINQ?
SELECT
Date,ShiftName,Max(Score) AS Score, 1 AS IsPreferred
FROM
[code]....
Convert SQL Query/subquery To LINQ (VB)?
Jan 16, 2012Here is my SQL query..
SELECT EqID, MakeID, Model, Description,
(SELECT MAX(EvDateEnd) AS MaxOfDateEnd
FROM tblEvent WHERE (EqID = tblEquip.EqID) AND (Event = 'REG')) AS RegExpire,
[code]....
For example, I want to get the Max EvDateEnd from the Events table for each record in tblEquip, but not all records in tblEquip have the "REG" event, while others have multiple REG events.Some events (like EAE) I leave the tblEvent.EvDateEnd field blank to show the event is open and ongoing, such as issuing a vehicle to an employee(entity). when the vehicle is returned I enter the date in EvDateEnd essentially closing the event.
Convert A LINQ Query Resultset To A DataTable?
Jul 20, 2010How can i write this query with LINQ to a FoxPro database?SELECT count(*) FROM Table group by item1I wrote it as below, but it doesn't work
Dim Query
Dim dt As New DataTable
Dim da = New Odbc.OdbcDataAdapter("SELECT * FROM table1",connection)
[code].....
Convert This String-based Sql Query To Use Linq?
Feb 3, 2011I have the following routine (that works) but which is messy to update owing to the hand-typed strings it uses:
Private Sub ListDefaults()
Dim conn As New SqlConnection( _
"server=bas047AUTODESKVAULT;Database=DWGDetails;Integrated Security=SSPI")
'Dim conn As New SqlConnection( _
[code]....
Use LINQ Query To Convert DBNull To String?
Oct 12, 2009I've created a small WPF app in VB9 to catalog our sizable DVD collection. This exercise has been more about learn programming than the need to have a movie database app, but I digress.The SQL database I created has a field for "Genre" that does not have an entry for all the movies in our collection. As such, when I run the method that filters the movie listing by "Genre" the compiler throws the "StrongTypingException was unhandled" error stating "The value for column 'Genre' in table 'Movies' is DBNull.".
I now understand where the DBNull problem comes from and have been searching for several hours to find a VB solution that converts the DBNull fields to strings on the fly during the LINQ query. I've found many solutions people have tried but, since I'm quite new to all this, none of them have worked for me. Pasted below is the method that throws the exception.
[Code]...
VS 2008 Convert A String Into A Linq Query?
May 20, 2012Is there a way to convert a string into a linq query? Searching for those words brings up tons of stuff unrelated to what I'm trying to do..For instance, this works, of course...
Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apple" Select item)
But somehow I want to do this:
Dim strQuery = "From item in htMyTable.values where item(0) = " & CHR(34) & "Apples" & CHR(34) & " Select item"
Dim lstMyQuery = (Somehow run/convert strQuery as a query)
The reason is strQuery will be different each time depending on what the user has selected earlier in the program.R if lstMyQuery is already a collection, is there a way to add to it?
Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apples" Select item)
(this obviously doesn't work, but it's basically what I want to do...)
lstMyQuery.Add(From item in htMyTable.values where item(0) = "Oranges" Select item)
Asp.net - Convert SQL (Pseudocode) To Dymanic LINQ Query From List<Custom> Parameters?
Apr 5, 2012GOAL: Bind nested ListViews to LINQ generated iQueryable of anonymous type. I want to use LINQ because you can use GroupBy and bind the nested ListView to the 'it' keyword.
SETUP: I have groups of sets of conditions. Each set of conditions is stored in the BillingCodes table. Each group of BillingCodes is stored in the BillingGroups table.
I have a custom object that stores the ID, Name, and NumCodes for each BillingGroup that the user has chosen.I have a collection of these objects called GroupsList that has a list of the groups that the user has chosen.
Problem 1: I can iterate through GroupsList and grab all the IDs. How do I translate the SQL 'WHERE ID IN(a string of comma delineated IDs)' for LINQ to SQL? Is that the best way to do that?
Problem 2: Once I have the list of BillingGroups I need to iterate through each group. For each group, I need to iterate through the BillingCodes. For each BillingCode I need to generate a WHERE clause that has all of the conditions in the BillingCode. I propose something like so:
for each BillingGroup in BillingGroups
for each BillingCode in BillingGroup.BillingCodes
where1 = "..."
next
next
Problem 3: Here's the part where I don't have a clue. I need to dynamically create a query in LINQ to SQL. Keep in mind that I don't know how many groups there'll be or how many codes are in each group.
There are 2 tables:
**transactions**
transaction_id
patient_id
[code]....
Convert A Two-table Exists Query From SQL To Linq Using Dynamic Fields In The Subquery?
Jun 7, 2011I'm trying to query old Access database tables and compare them with SQL Server tables.They often don't have primary keys, or they have extra fields that had some purpose in the nineties, etc., or the new tables have new fields, etc.I need to find records - based on a set of fields specified at runtime - that are in one table but not another.So, I do this kind of query all the time in SQL, when I'm comparing data in different tables:
dim fields_i_care_about as string = "field1, field2, field3"
'This kind of thing gets set by a caller, can be any number of fields, depends on the
'table
dim s as string= ""
[code]....
It tells me it can't convert a Boolean - Is there any way to do this without Linq expressions? They seem far more complex than what I'm trying to do here, and they take a lot of code, and also I can't seem to find examples of Expressions where we're comparing two fields in a subquery.Is there a simpler way? I know I could do the usual EXISTS query using JOIN or IN - in this case I don't need the query to be super fast or anything. And I don't need to use a DataTable or DataSet - I can put the data in some other kind of object.
Convert A List Linq Expression To Defined List Class?
May 26, 2012y have this class
Private Class MyClass
Public Property propertyOne() as String
Public Property propertyTwo() as String
[code].....
LINQ Query Is Enumerated - Turn On Some Kind Of Flag That Alerts Me Each Time A LINQ Query Is Enumerated?
Sep 22, 2009I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
.net - ActiveRecord Linq/NHibernate Linq Not Building Query Completely?
Jul 14, 2011given this function:
Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _
[Code]....
instead of what I expected:
Select count(*) from remitline where lastname = "smith"
What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1
Performance Gain In LINQ Query Vs LINQ Stored Procedure?
Aug 6, 2009if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesAsp.net - Complex Linq Query - Add A .Where() Or .Any() Predicate To Reduce Query Complexity (in VB)?
Sep 14, 2010I have to join two main tables, and I need to filter the results by elements in an ASP.NET web form. These filters are created on the fly so I have to use a lot of where extensions to filter the query. I want to execute the query with as optimized SQL as possible.
I am first doing a simple join between TW_Sites and TW_Investigators. Then there are two sub-tables that are involved. TW_InvestigatorToArea and TW_InvestigatorToDisease. While most of the where clauses are working fine, I have found a performance issue that won't be an issue right now, but will be an issue as the table gets bigger.
The arrays DiseaseCategories and DiseaseAreas would be the results of a CheckBoxList result.
Protected Sub LoadResults()
'Get Dictionary of Filters
Dim FilterDictionary As OrderedDictionary = Session.Item("InvestigatorFilterDictionary")
' Initialize LinqToSql
[code]....
LINQ Query Using The Dynamic LINQ Library?
Mar 31, 2011Forgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
Linq Expression To .net?
Nov 17, 2009convert this C# code to VB, tried couple of converters and they dont work properly.
[Code]...
Converting LINQ Expression From C#
Nov 18, 2010I'm having a little trouble converting some LINQ to VB.[code]Online code translators are not helping, and my unfamiliarly with VB LINQ is not very good.
View 2 RepliesVS 2010 Use Take() With Linq Expression?
Aug 6, 2011THE CODE IS :
var query1 = ((from c in dt.AsEnumerable()
orderby c.Field<int>("1") descending
select c));
var query2 = (from c in query1.Take(10)
select c);
[Code]...
.NET XML Literal Expression Expected With Linq To XML?
Jun 9, 2010I have the same problem as stated in this question, but the accepted solution there was a "works on my machine" answer.
[Code]...
And I receive the error: BC30201: Expression expected.
Does anyone have a more detailed idea of what could cause this?
C# - Join The Objects In A LINQ Expression?
Dec 15, 2011How to Join the objects in a LINQ select in this sample (C# variants accepted as well):
Class Room
Public Area As Integer
End Class
Class RoomPair
[code]....
Dynamic Linq Expression Tree After Where
Oct 28, 20111) I am begginner to dynamic Linq and having serious trouble creating expression tree after WHERE
say.: items.Category_ID=4
I tried to construct it like: Dim products = From items In mydatacontent.Products
Dim AA As ParameterExpression = Expression.Parameter(GetType(String), "items")
Dim left1 As Expression = Expression.Property(AA, GetType(String).GetProperty("Category_ID")) here is the error Dim right1 As Expression = Expression.Constant("4") Dim BB As Expression = Expression.Equal(left1, right1)
[Code]...
Linq - .NET Logical Expression Evaluator?
May 21, 2010I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically)For example the resulting string may contain "'dog'<'cat' OR (1>4 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = > < >< >= <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.)
I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project.
class ExpressionEvaluator
{
function Evaluate(Expression : String)
{
return eval(Expression);
}
}
Is there a simpler method using built in .NET functions or Lamdba expressions.
Linq - Examples Of .NET Lambda Expression?
Feb 3, 2011Where can I find complex LINQ examples made using VB.NET Lambda Expression syntax?During my searches I always found 101 LINQ Samples but they use the other notation and for me is not always clear how to transform that code into a lambda expression.
View 1 RepliesLINQ Expression Starting With From And Aggregate
May 4, 2012[code]The LINQ query going into "result" is incomplete because I'm stumped at what is happening there. I expect FirstOrDefault to refer to refer to a single Child object at that point in the expression, but it refers to a collection of child objects. Why? What is the best way to get a list of parents that have no associated child or have a child fitting a particular condition? (My actual code will have one child max, so this sample code is not representative.)I just don't understand what the collection of FirstOrDefault could be referring to. It should really be just 1 value or nothing at all times.
View 1 RepliesVS 2008 Translate C# Linq Expression?
Nov 28, 2010translation of the following C# Linq Expression (in VB.NET 2008):
syncContext.Send((obj) => eventToBeFired(this, new EventArgs()), null);
Is used in this subroutine:
private void FireEvent(EventHandler eventToBeFired)
{
if (eventToBeFired != null)
{
[code]....