Parameters to the EXISTS clause in a stored procedure

Question

I have a table DEPT, which holds 2 columns - ID, NAME.

A search form is presented with the IDs from the DEPT table and the user can chose any number of IDs and submit the form, to get the related NAMEs.

Clarification/Inputs:

• I don't want to build a dynamic query - its not manageable.
• I prefer a stored procedure using table-valued parameters

Any other solutions to proceed?

NOTE:
This example is simple with 1 table - in real life, I have to deal with more than 6 tables!

Thanks for any suggestions

Answer 1

CREATE TYPE dbo.DeptList
AS TABLE
(
  ID INT
);
GO

CREATE PROCEDURE dbo.RetrieveDepartments
  @dept_list AS dbo.DeptList READONLY
AS
BEGIN
  SET NOCOUNT ON;

  SELECT Name FROM dbo.table1 WHERE ID IN (SELECT ID FROM @dept)
  UNION ALL 
  SELECT Name FROM dbo.table2 WHERE ID IN (SELECT ID FROM @dept)
  -- ...
END
GO

Now in your C# code, create a DataTable, fill it in with the IDs, and pass it in to the stored procedure. Assuming you already have a list called tempList and the IDs are stored in id:

DataTable tvp = new DataTable();
tvp.Columns.Add(new DataColumn("ID"));

foreach(var item in tempList)
{ 
    tvp.Rows.Add(item.id); 
}

using (connObject)
{
    SqlCommand cmd = new SqlCommand("StoredProcedure", connObject);
    cmd.CommandType = CommandType.StoredProcedure;
    SqlParameter tvparam = cmd.Parameters.AddWithValue("@dept_list", tvp);
    tvparam.SqlDbType = SqlDbType.Structured;
    ...
}

You can also use a split function. Many exist, this is the one I like if you can guarantee that the input is safe (no <, >, & etc.):

CREATE FUNCTION dbo.SplitInts_XML
(
   @List       VARCHAR(MAX),
   @Delimiter  CHAR(1)
)
RETURNS TABLE
AS
   RETURN 
   (  
      SELECT Item = y.i.value('(./text())[1]', 'int')
      FROM 
      ( 
        SELECT x = CONVERT(XML, '<i>' 
        + REPLACE(@List, @Delimiter, '</i><i>') + '</i>').query('.')
      ) AS a 
      CROSS APPLY x.nodes('i') AS y(i)
   );
GO

Now your procedure can be:

CREATE PROCEDURE dbo.RetrieveDepartments
  @dept_list VARCHAR(MAX)
AS
BEGIN
  SET NOCOUNT ON;

  ;WITH d AS (SELECT ID = Item FROM dbo.SplitInts(@dept_list, ','))
  SELECT Name FROM dbo.table1 WHERE ID IN (SELECT ID FROM d)
  UNION ALL
  SELECT Name FROM dbo.table2 WHERE ID IN (SELECT ID FROM d)
  -- ...
END
GO