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Use Table-Valued Parameters (Database Engine)

Topic Status: Some information in this topic is preview and subject to change in future releases. Preview information describes new features or changes to existing features in Microsoft SQL Server 2016 Community Technology Preview 2 (CTP2).

Table-valued parameters are declared by using user-defined table types. You can use table-valued parameters to send multiple rows of data to a Transact-SQL statement or a routine, such as a stored procedure or function, without creating a temporary table or many parameters.

Table-valued parameters are like parameter arrays in OLE DB and ODBC, but offer more flexibility and closer integration with Transact-SQL. Table-valued parameters also have the benefit of being able to participate in set-based operations. 

Transact-SQL passes table-valued parameters to routines by reference to avoid making a copy of the input data. You can create and execute Transact-SQL routines with table-valued parameters, and call them from Transact-SQL code, managed and native clients in any managed language.

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Table-Valued Parameters vs. BULK INSERT Operations


A table-valued parameter is scoped to the stored procedure, function, or dynamic Transact-SQL text, exactly like other parameters. Similarly, a variable of table type has scope like any other local variable that is created by using a DECLARE statement. You can declare table-valued variables within dynamic Transact-SQL statements and pass these variables as table-valued parameters to stored procedures and functions.

Table-valued parameters offer more flexibility and in some cases better performance than temporary tables or other ways to pass a list of parameters. Table-valued parameters offer the following benefits:

  • Do not acquire locks for the initial population of data from a client.

  • Provide a simple programming model.

  • Enable you to include complex business logic in a single routine.

  • Reduce round trips to the server.

  • Can have a table structure of different cardinality.

  • Are strongly typed.

  • Enable the client to specify sort order and unique keys.

  • Are cached like a temp table when used in a stored procedure. Starting with SQL Server 2012, table-valued parameters are also cached for parameterized queries.

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Table-valued parameters have the following restrictions:

  • 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.

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Using table-valued parameters is comparable to other ways of using set-based variables; however, using table-valued parameters frequently can be faster for large data sets. Compared to bulk operations that have a greater startup cost than table-valued parameters, table-valued parameters perform well for inserting less than 1000 rows.

Table-valued parameters that are reused benefit from temporary table caching. This table caching enables better scalability than equivalent BULK INSERT operations. By using small row-insert operations a small performance benefit might be gained by using parameter lists or batched statements instead of BULK INSERT operations or table-valued parameters. However, these methods are less convenient to program, and performance decreases quickly as rows increase.

Table-valued parameters perform equally well or better than an equivalent parameter array implementation.

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The following example uses Transact-SQL and shows you how to create a table-valued parameter type, declare a variable to reference it, fill the parameter list, and then pass the values to a stored procedure.

USE AdventureWorks2012;

/* Create a table type. */
( LocationName VARCHAR(50)
, CostRate INT );

/* Create a procedure to receive data for the table-valued parameter. */
CREATE PROCEDURE dbo. usp_InsertProductionLocation
    @TVP LocationTableType READONLY
    INSERT INTO AdventureWorks2012.Production.Location
        SELECT *, 0, GETDATE()
        FROM  @TVP;

/* Declare a variable that references the type. */
DECLARE @LocationTVP AS LocationTableType;

/* Add data to the table variable. */
INSERT INTO @LocationTVP (LocationName, CostRate)
    SELECT Name, 0.00
    FROM AdventureWorks2012.Person.StateProvince;

/* Pass the table variable data to a stored procedure. */
EXEC usp_InsertProductionLocation @LocationTVP;

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