How Can I Use Table Variables in Dynamic SQL Statements Effectively?

Effective use of table variables in dynamic SQL statements

In some cases, developers may encounter errors when trying to use table variables in dynamic SQL statements. This error is caused by the need to explicitly declare table variables in dynamic SQL statements.

To resolve this issue, when using SQL Server 2008 or later, consider using table-valued parameters (TVP) to pass table variables into dynamic SQL statements. TVP provides a way to directly use table variables for dynamic queries.

An important thing to note is that TVP does not allow updates to table variables in dynamic SQL statements. Therefore, it is recommended to declare table variables explicitly in dynamic SQL statements if updates are required.

To illustrate the use of table variables in dynamic SQL statements using TVP, consider the following code snippet:

CREATE TYPE MyTable AS TABLE
(
FOO INT,
BAR INT
);

DECLARE @T AS MyTable;

INSERT INTO @T VALUES (1,2), (2,3)

SELECT *,
        sys.fn_PhysLocFormatter(%%physloc%%) AS [physloc]
FROM @T

EXEC sp_executesql
  N'SELECT *,
        sys.fn_PhysLocFormatter(%%physloc%%) AS [physloc]
    FROM @T',
  N'@T MyTable READONLY',
  @T=@T

In this example, a table type named MyTable is created. A table variable @T is declared and data is inserted into it. Use the sys.fn_PhysLocFormatter function to select and process data in table variables. Finally, use the sp_executesql stored procedure to execute the dynamic SQL statement and pass the table variable @T as a TVP with the READONLY option.

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