Table Valued Parameters

Before SQL Server 2008 the most common way to pass data from one procedure to another would be by creating a temporary table, fill it with the required data and then call another procedure that uses that temporary table. Although this is not a disaster it does have some flaws like not being strongly typed. The weak typing of temp tables in this scenario make it a perfect spot for issues. There are other solutions using XML but these tend to be more complex than necessary for the 'simple' thing you are trying to do... pass structured data around.

SQL Server 2008 now supports something called Table Valued Parameters (or TVP) which can help you in these situations. TVP's make it possible to use a "table" as a parameter for a procedure. A couple of limitations apply, TVP's can only be READONLY in the procedure that define them as a parameter and they can only be used as an input parameter. Apart from this the same rules apply to TVP's as to table variables for example no DDL can be executed against a TVP and no statistics are kept for TVP's.

A little example will make it very clear.

--Create test table
CREATE TABLE myUsers
(ID int, UserName varchar(50), UserRole tinyint);
GO

--Create the required type
CREATE TYPE UserRoleType AS TABLE
( UserRole tinyint );
GO

--Create procedure that takes the type as a parameter (READONLY is required)
CREATE PROCEDURE GetUsersInRole
@UserRoleType UserRoleType READONLY
AS
SELECT UserName
FROM myUsers u
INNER JOIN @UserRoleType ut ON u.UserRole = ut.UserRole
GO

--Insert some test data (multiple inserts in one go, another new feature)
INSERT INTO myUsers
VALUES (1, 'Wesley', 1),
(2, 'Tom', 2),
(3, 'Patrick', 2),
(4, 'Jan', 3),
(5, 'Bregt', 3)

--Throw in a new dmv to look at the type and check dependencies if you like
--SELECT * FROM sys.table_types
--SELECT * FROM sys.dm_sql_referenced_entities ('dbo.GetUsersInRole', 'OBJECT')
GO

--Lookup action
DECLARE @UserRoleType
AS UserRoleType;

--Lets use another new features (initialize var on declare!)
DECLARE @Admin tinyint = 1
DECLARE @PowerUser tinyint = 2
DECLARE @User tinyint = 3

--Add parameter values to the table valued parameter
--INSERT INTO @UserRoleType VALUES (1), (2)
INSERT INTO @UserRoleType VALUES (@Admin), (@PowerUser)

--Call stored procedure with specific type (remember the post is about table valued parameters)
EXEC GetUsersInRole @UserRoleType;
GO

--Clean up
DROP PROCEDURE GetUsersInRole
DROP TYPE UserRoleType
DROP TABLE myUsers