Dynamic SQL To Dynamic LINQ In .NET With MS SQL Server 2008?
May 24, 2010
I need to represent the following query using LINQ:
DECLARE @PurchasedInventoryItemID Int = 2
DECLARE @PurchasedInventorySectionID Int = 0
DECLARE @PurchasedInventoryItem_PurchasingCategoryID Int = 3
DECLARE @PurchasedInventorySection_PurchasingCategoryID Int = 0
[code]....
Now, I know that a query in .NET doesnt look like this, this is my test in the SQL Design Studio. Naturally VB.NET variables will be used in place of the SQL local variables.My problem is this: All of the conditions after "WHERE" are optional. In that a query might be made that uses one, some, all, or none of the conditions. V.PropertyID and V.Value can also appear any number of times.In VB.NET I can make this query easy enough by simply concatenating strings, and using a loop to append the "V.PropertyID/V.Value" conditions.I can also make a Stored Procedure in MS SQL, which is easy enough.However, I want to accomplish this using LINQ.
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Feb 5, 2010
I would like to bind a DataGridView to a different LINQ query every time (in order to reuse the same form/DGV for different queries), like this:
[Code]....
but the "Qry", and the number of comboboxes, and their field names would change every time.
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Oct 17, 2011
This is an extension of my last question which was answered, so I am starting a new thread. I have a query in LINQ that I was given to trim down the columns of a datatable. This works well, however, I need to make the LINQ query dynamic. So the query below:
Dim qColumnsIWant = From row As DataRow In inDT.AsEnumerable() _
Select _
EPN = row.Field(Of Integer)("EPNID"), _
EPNID = row.Field(Of String)("EPNNumber"), _
Ingot = row.Field(Of String)("Ingot"), _
ShopOrder = row.Field(Of String)("ShopOrder")
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Feb 19, 2010
Ive managed to dynamically create a form, and dynamically create a timer, but i have not been able to create the timer on the dynamic form. Specifically, i need to be able to have the timer itself create another form with a timer. (I realize that this would create a new form every interval on the timer, that is what i want to do)
1. A way to add the timer to the dynamic form, and maintain the timer sub on my main form.
2. A way to create the whole thing over (dynamic form and timer) through the previous dynamic form and timer.
I was thinking i could use a collection/array to store the forms and timers, but i'm still having trouble figuring out how to add entire forms or timers into a list. (A timer is not considered a control, so i cant use a controlcollection...)
Heres my code;
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim frm As New Form
[Code]....
*EDIT* Btw, my idea was to use i as a variable that increases every time a form is created, then insert the form into the array, with i as the integer. i just need to know how to create a new form with a different name each time. (as with timers)
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Jun 5, 2008
I've recently ported my website from 2005 to 2008, and I'm using LINQ Queries to implement a search. The issue is that none of the fields are mandatory, so I've had to implement a dynamic LINQ Query (sic?). Here's the relevant code -
Public Function searchQuery(ByVal titleType As String, ByVal titleName As String, _
ByVal configMgr As String, ByVal lifecycle As String, _
ByVal CIType As String, ByVal recordsPerPage As String) As IEnumerable(Of
[code].....
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Oct 19, 2010
Can i create a table with the input taken from user at runtime from vb.net.?
From vb.net in sqlserver 2008
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Jan 28, 2010
In a nutshell, I am selecting values from a checked box column in a grid view. After checking the boxes I have a function that concatenates each customer number into a string called @CusList to use a parameter for a stored procedure Public Function SelectCusList()
Dim CusShow As String
Dim CusStr As String
Dim CusList As String
CusStr = ""
[Code]...
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Sep 10, 2009
Example-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[Code]...
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Mar 31, 2011
Forgive 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."
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May 8, 2011
i have created a dynamic tabpage and a dynamic tablelayoutpanel inside it then added dynamic textboxes and labels inside the tablelayoutpanel...the thing is , i am having a problem on how to access the value of those textboxes and labels and add them as new columns in the new table(tagpage) in mysql database, i can already create the table in the database but i cant add the new columns in it. heres the code for accessing the values of the labels and textboxes
error: NullReferenceException was unhandled....Object variable or With block variable not set.
sql = "alter table " & tbl_selected(counter) & " add " & frmMain.Controls("TLP_" & SecArrList_sp(counter2)).controls.item(SecArrList_sp(counter2) & "label" & counter).Text & " varchar(100) NULL;"
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Sep 14, 2010
How would I get something like this to work so that I can dynamically alter the where-clause in this linq to sql query?
Dim AccountID = 1234
Dim AccountList
Select Case Types
[Code]....
With the above code I get this error:
Late binding operations cannot be converted to an expression tree
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Feb 29, 2012
Basically i have one TabControl with a form and 2 browsers within one form I have ProBlem To call the dynamic browser to navigate with dynamic Textbox.text
[Code]...
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Mar 14, 2011
I have been trying the following but it returns unexpected results:
Dim xd As XDocument = _
<?xml version="1.0" encoding="utf-8"?>
<root>
[code].....
The above result returns both 'element' nodes however it should only return the first where element/subelement@id=1/subsubelement@id=3 However if results.Ancestors. is used it returns the correct 'subelement' and if that line is not included it returns a single 'subsubelement' whih is also correct I don't understand why when mvoing to the 'element' it returns both (I realise both have a subelement with id=1 but I thought each further query would filter out the presvious results)?
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Feb 24, 2012
UPDATE: Groo's answer was marked correct as it would be a good alternative. I decided to stick with the select/switch statements to avoid the performance issues of using reflection. As far as I can tell there is no way to do what I want without using Dynamic LINQ (and reflection) or a decompiler (to manually code each LINQ statement, which I am already doing by hand). Note: to make this update DropDownList16 through DropDownList20 were removed (needed the characters).Is there a way to abstract the building of a dynamic Linq to SQL query?
I am trying to build a Linq to SQL query with a dynamic where clause, based on user supplied filters. The user needs to be able to filter strings, integers, and dates using advanced options (equal, not equal, contains, starts with, etc). The user needs to be able to use these filters with as many or few columns as desired.
[Code]...
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Jan 5, 2010
Dim query=Form f in BBSDb.Forms order by f.FormID Descending Select f where I want the f.FormID to be able to replace with a variable..What I mean is.. it doesn't have to f.FormID .. I may want to set f.FormName to be in descending for example using the code dynamically.. Is there anyway to achive?
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Mar 16, 2011
I want to write a query that the "where" in the query is a string something like"
Dim query as string= "Name =xxxx and Date > 10 "
Dim t = from book in doc.Descendants("books") Select _
[Name] = book..value, [Date] = book..value....
Where (query)
I build the query string on run time
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Jan 24, 2010
I have been looking into dynamic querying of datasets and the use of copytodatatable() for a project. I have seen in alot of forums that the copytodatatable functionality is unusable as it was removed. have an example of a dynamic Linq query being loaded into a datatable.
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Jun 28, 2011
I have the following linq query:
Dim q = From definition In definitionList _
Where definition.ValueDefName.Contains(criteria)[code]....
I have already looked into this answer: LINQ - dynamic WHERE clause?Unfortunately, it doesn't work for me using .net 4.0. When I attempt to pass the criteria string in it ask for a predicate. The end goal is to add any of these:
definition.ValueDefname.Contains(criteria)
definition.ValueDefDesc.Contains(criteria)
definition.Aliaslist.Contains(Criteria)
definition.StrategicInitiative.Contains(Criteria)
to be passed into the query depending on what checkboxes the user has selected. How can I create a dynamic where clause in linq to sql? Is there new syntax for passing in a where clause as a string?
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Mar 16, 2011
I have a listbox which users can select from a list if Towns, I want to be able to build a LINQ query based on the selected items in the list e.g.
[Code]...
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Apr 13, 2012
I'm need to do the equivalent of a t-sql statement like this using LINQ:
SELECT * FROM mytable WHERE idnumber IN('1', '2', '3')
so in LINQ I have:
Dim _Values as String = "1, 2, 3"
Dim _Query = (From m In mytable Where idnumber = _Values Select m).ToList()
Not sure what to do with _Values to make idnumber evaluate each value in the string.
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Oct 28, 2011
1) 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]...
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Aug 9, 2010
How do i great dynamic linq query in VB.net?
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May 3, 2011
I'm trying to implement multicolumn filtering using LINQ expressions in a class that extends BindingList(Of T). Here is the relevant code:
Public Function GetFilterPredicate() As Func(Of T, Boolean)
Dim expressionList As List(Of Expression) = New List(Of Expression)
For Each item as FilterInfo in _FilterList
[code]....
However, an exception is thrown at the Expression.Call statement. I can't quite figure out the right arguments to supply. As it is now, I am getting this error when I run the code:
InvalidOperationException was unhandled:No generic method 'Equal' on type 'System.Linq.Expressions.Expression' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic.
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Jun 20, 2012
I'm having a problem implementing Scott G's Dynamic.vb extension at [URL] in my vb solution. I've searched StackOverflow (80+ Q&As) and numerous other sites without much luck. I'm using VS 2010.I've included Dynamic.vb in a problem with no root namespace, and then added a reference to that project in my main one. I'm getting intellisense for 4 overloads (rather than 2) so I'm pretty certain that the extension is in scope.I was having a tough time with clauses, especially the OrderBy as Scott demonstrated. If I simply pass a string as Scott's VB example did I get the error "Overload resolution failed because no accessible 'OrderBy' can be called with these arguments."
The line of code is:
Dim FilteredComponentList = From Component As MX.Component In ComponentList.AsQueryable _
.OrderBy("Name")
So I found other references that stated to pass a Lambda expression. So I tried this and at least I get no error, even if the sort function still doesn't seem to work. Here is the code that compiles and executes.
Private Sub SortByColumn()
If Not cmbComponentFilter.SelectedItem.ToString = "All" Then
Dim FilteredComponentList = From Component As MX.Component In ComponentList.AsQueryable _
[code]....
When I interrogate the dgvComponents.Columns(e.ColumnIndex).Name it gives the objects property I wish to sort by, but the sort still isn't working. I'm concerned why I can't get Scott's implementation to work, but I've heard his keynotes and read his blogs, so I'm guessing the problem lies with my implementation.
I'd like either to work but need to understand why as well. Why doesn't passing a string work? Isn't the PARAMARRAY declared in the function optional?
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Jan 5, 2011
I want to create a simple function that does the following:
Sub SetValue(Of TInstance As Class, TProperty)(
ByVal instance As TInstance,
ByVal [property] As Expression(Of Func(Of TInstance, TProperty)),
[code].....
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Nov 23, 2009
I have a listbox that is dynamically filled by certain values depending on what table has been selected from another list box. Once a value is selected, it is being graphed vs a date & time range. With my ignorance of linq: depending on what value is selected, the linq to sql statement I need to create to grab data from my database is different as I can't use an index on an anonymous type.
result = From t In db.APS _
Where t.DateTime >= startDate And _
t.DateTime <= finishDate And t.Weight = weight _
Select t.DateTime, t.TotalConcentration
t.TotalConcentration should be selected if my listbox value is "Total Concentration", but if it's something else, like "Temperature" or "Flow Rate" (connected to appropreate database columns) - this method obviously isn't going to work. I need to be able to dynamically select a specific column from the anonymous type list, or use some other method I'm unaware of to do this.
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Nov 3, 2009
I am looking for sample linq code snippet which uses System.Linq.Dynamic against a datatable.
Dim entities = (From ent In dt.AsEnumerable().Where(String.Format("IsUSFederal == {0}", "true")) _
Select Description = ent("Description"), Acronym = ent("Acronym")).ToList
I am getting an error "there is no accessible Where can be called with these arguments". I have included the DynamicLinq.vb file and the application compiles fine (aside from this error). I have included Imports System.Linq.Dynamic but it doesn't appear to be working.
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Feb 17, 2011
I use the following code to fill the Table1 dictionary with the information found within the LINQ query.
Dim DB As New DatabaseDataContext
Dim Table1 As New Dictionary(Of String, Integer)
Dim Table2 As New Dictionary(Of String, Integer)
[code].....
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Jan 13, 2011
How can I use dynamic fields in LINQ in the PART OF THE where query? I mean that I want to write where x = *dynamic fields* I want to do the select query in all of the tables that are in the dataset, not on one datatable.
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Feb 17, 2011
I'm developing an application to allow engineers to conduct simple single table/view queries against our databases by selecting Database, Table, Fields.
I get how to use the Dynamic LINQ Library Sample to provide for dynamically selecting the Select, Where and Order by Clauses at runtime but I'm at an impass on how to allot for table choice.
Is there a way to provide for dynamically selecting the "from" table at run time
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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