Parameters (Database Engine)
Parameters are used to exchange data between stored procedures and functions and the application or tool that called the stored procedure or function:
- Input parameters allow the caller to pass a data value to the stored procedure or function.
- Output parameters allow the stored procedure to pass a data value or a cursor variable back to the caller. User-defined functions cannot specify output parameters.
- Every stored procedure returns an integer return code to the caller. If the stored procedure does not explicitly set a value for the return code, the return code is 0.
The following stored procedure shows the use of an input parameter, an output parameter, and a return code:
-- Create a procedure that takes one input parameter
-- and returns one output parameter and a return code.
CREATE PROCEDURE SampleProcedure @EmployeeIDParm INT,
@MaxTotal INT OUTPUT
AS
-- Declare and initialize a variable to hold @@ERROR.
DECLARE @ErrorSave INT
SET @ErrorSave = 0
-- Do a SELECT using the input parameter.
SELECT FirstName, LastName, JobTitle
FROM HumanResources.vEmployee
WHERE EmployeeID = @EmployeeIDParm
-- Save any nonzero @@ERROR value.
IF (@@ERROR <> 0)
SET @ErrorSave = @@ERROR
-- Set a value in the output parameter.
SELECT @MaxTotal = MAX(TotalDue)
FROM Sales.SalesOrderHeader;
IF (@@ERROR <> 0)
SET @ErrorSave = @@ERROR
-- Returns 0 if neither SELECT statement had
-- an error; otherwise, returns the last error.
RETURN @ErrorSave
GO
When a stored procedure or function is executed, input parameters can either have their value set to a constant or use the value of a variable. Output parameters and return codes must return their values into a variable. Parameters and return codes can exchange data values with either Transact-SQL variables or application variables.
If a stored procedure is called from a batch or script, the parameters and return code values can use Transact-SQL variables defined in the same batch. The following example is a batch that executes the procedure created earlier. The input parameter is specified as a constant and the output parameter and return code place their values in Transact-SQL variables:
-- Declare the variables for the return code and output parameter.
DECLARE @ReturnCode INT
DECLARE @MaxTotalVariable INT
-- Execute the stored procedure and specify which variables
-- are to receive the output parameter and return code values.
EXEC @ReturnCode = SampleProcedure @EmployeeIDParm = 19,
@MaxTotal = @MaxTotalVariable OUTPUT
-- Show the values returned.
PRINT ' '
PRINT 'Return code = ' + CAST(@ReturnCode AS CHAR(10))
PRINT 'Maximum Quantity = ' + CAST(@MaxTotalVariable AS CHAR(10))
GO
An application can use parameter markers bound to program variables to exchange data between application variables, parameters, and return codes.
See Also
Concepts
Parameter Markers (Database Engine)
Other Resources
Stored Procedures (Database Engine)
CREATE PROCEDURE (Transact-SQL)
DECLARE @local\_variable (Transact-SQL)