Why are table valued parameters to SQL Server stored procedures required to be input READONLY?

Question

Can anyone explain the design decision behind preventing table valued parameters from being specified as output parameters to stored procedures?

I can\'t count the n

Answer 1

Table-valued parameters have the following restrictions(source MSDN):

• SQL Server does not maintain statistics on columns of table-valued parameters.
• Table-valued parameters must be passed as input READONLY
  parameters to Transact-SQL routines. You cannot perform DML
  operations such as UPDATE, DELETE, or INSERT on a table-valued
  parameter in the body of a routine.
• You cannot use a table-valued parameter as target of a SELECT INTO or INSERT EXEC statement. A table-valued parameter can be in the FROM clause of SELECT INTO or in the INSERT EXEC string or stored procedure.

there are few options to over come this restriction one is

CREATE TYPE RTableType AS TABLE(id INT, NAME VARCHAR )

go

CREATE PROCEDURE Rproc @Rtable RTABLETYPE READONLY,
                       @id     INT
AS
  BEGIN
      SELECT *
      FROM   @Rtable
      WHERE  ID = @id
  END

go

DECLARE @Rtable RTABLETYPE
DECLARE @Otable RTABLETYPE

INSERT INTO @Rtable
VALUES      (1,'a'),
            (2,'b')

INSERT @Otable
EXEC Rproc
  @Rtable,
  2

SELECT *
FROM   @Otable 

through this you can get the table values out