How do I provide a string with a list of values to an "IN" statement

Question

I am creating a string that is a list of comma-delimitted values by looping through the selections in a CheckBoxList. I am able to display this value, so I know that it is creating what I expect. I am attempting to pass this list to an IN statment in a SELECT query:

SelectCommand="SELECT ThisDate, DATEPART(dw, ThisDate) AS Expr1 FROM fbCalendar WHERE (ThisDate >= @ThisDate) AND (ThisDate <= @ThisDate2) AND (DATEPART(dw, ThisDate) IN (@TheseDays))"

<asp:ControlParameter ControlID="Label1" Name="TheseDays" PropertyName="Text" Type="String" />  

This works fine as long as there is only a single item selected, but selecting a second item fails with the message: Conversion failed when converting the nvarchar value '4,5' to data type int.

However, I do not understand when this would be converted to an INT. I have tried many different formatting attempts (such as encapsulating the string in parenthesis (e.g. "(4,5)" ) for the SELECT query, but I have yet to find the right one to make this work. It seems like formatting is the problem, but perhaps I am missing something else.

Answer 1

Degan.

I created a table to store the values to pass to the query. It just doesn't seem right.

You don't have to create an actual table. You can use a Table Valued Function and use that in your query e.g. as below.

(DATEPART(dw, ThisDate) IN (SELECT [item] FROM dbo.fnSplit(@TheseDays, ',')))

This uses the TVF from http://www.eggheadcafe.com/community/aspnet/13/10021854/fnsplit.aspx).

CREATE FUNCTION dbo.fnSplit(
    @sInputList VARCHAR(8000) -- List of delimited items
  , @sDelimiter VARCHAR(8000) = ',' -- delimiter that separates items
) RETURNS @List TABLE (item VARCHAR(8000))

BEGIN
DECLARE @sItem VARCHAR(8000)
WHILE CHARINDEX(@sDelimiter,@sInputList,0) <> 0
 BEGIN
 SELECT
  @sItem=RTRIM(LTRIM(SUBSTRING(@sInputList,1,CHARINDEX(@sDelimiter,@sInputList,0)-1))),
  @sInputList=RTRIM(LTRIM(SUBSTRING(@sInputList,CHARINDEX(@sDelimiter,@sInputList,0)+LEN(@sDelimiter),LEN(@sInputList))))

 IF LEN(@sItem) > 0
  INSERT INTO @List SELECT @sItem
 END

IF LEN(@sInputList) > 0
 INSERT INTO @List SELECT @sInputList -- Put the last item in
RETURN
END
GO