A number of other query elements preclude auto-parameterization. By default, SQL Server won’t autoparameterize queries containing any of these constructs:
- IN clauses
- BULK INSERT
- UPDATE statement with SET clause that contains variables
- A SELECT statement with UNION
- A SELECT statement with INTO clause
- A SELECT or UPDATE statement with FOR BROWSE clause
- A statement with query hints specified using the OPTION clause
- A SELECT statement whose SELECT list contains a DISTINCT
- A statement with the TOP clause
- A WAITFOR statement
- When a SELECT query contains a subquery or JOIN
- When a SELECT statement has GROUP BY, HAVING, or COMPUTE BY
- Expressions joined by OR in a WHERE clause
- Statements submitted via EXEC string
- INSERT... EXEC statement
In other words, SQL Server will autoparameterize only the simplest queries.