Scalar UDFs

Scalar UDFs return a single (scalar) value. They can be specified where scalar expressions are allowed–for example, in a query, constraint, computed column, and so on. Scalar UDFs have several syntactical requirements. Scalar UDFs:

  • Must have a BEGIN/END block defining their body.

  • Must be schema qualified when invoked (unless invoked as stored procedures with EXEC, as in EXEC myFunction 3, 4).

  • Do not allow omitting optional parameters (ones that have default values) when invoked; rather, you must at least specify the DEFAULT keyword for those.

The following sections explore both T-SQL and CLR UDFs.

T-SQL Scalar UDFs

T-SQL UDFs are typically faster than CLR UDFs when the main cost of their activity pertains to set-based data manipulation, ...

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