T-SQL Return Multiple Result Sets

Question

I'm hopeful that this isn't too awkward a question, but my searches so far haven't shed much light on things. My apologies if it's been asked before.

I need to write a stored proc to run a simple query along the lines of

SELECT foo 
  FROM sometable 
 WHERE somecolumn = @parameter

and then, for each foo execute another query, and return the results from each one as a separate result set.

I don't need to return the results of the initial query, just the results of executing the second query against each value of foo, and I don't want them combined into one result set, despite all having the same columns (it simplifies the presentation logic a lot if I can return multiple result sets).

This is on SQL-Server 2008 R2.

Thank you.

Answer 1

You should use CURSOR in you stored procedure like this:

DECLARE @foo VARCHAR(XXX)

DECLARE Curs CURSOR FAST_FORWARD READ_ONLY FOR
SELECT 
    foo 
FROM sometable 
WHERE 
    somecolumn = @parameter

OPEN Curs

FETCH NEXT FROM Curs INTO @foo

WHILE @@FETCH_STATUS = 0
BEGIN

    -- here you should put actual query
    SELECT
    *
    FROM dbo.SomeTable
    WHERE
        foo = @foo

FETCH NEXT FROM Curs INTO @foo

END

CLOSE Curs
DEALLOCATE Curs

and then read cursor results using code like:

var sqlCommand = new SqlCommand("spYourStoredProcedure", connection)
sqlCommand.CommandType = CommandType.StoredProcedure;
var reader = sqlCommand.ExecuteReader();

do 
{
    while (reader.Read())
    {
        // DO SOMETHING
    }
} while(reader.NextResult());

Answer 2

You could put the results of your SELECT statement into a cursor then loop through the cursor performing the second query against foo

This article explains cursors quite nicely

http://www.mssqltips.com/sqlservertip/1599/sql-server-cursor-example/