Because they reside at the server, they reduce network round trips for queries and improve performance. They also simplify version control because they encapsulate logic that is resident in one place instead of across several clients. Stored-procedure languages vary, but ODBC and JDBC provide a uniform method for calling procedures. The procedure-call escape clause can execute procedures with or without parameters. Example 3 .
Parameters can be a literal, a parameter marker, or unspecified.
Procedures that return result sets do not require any special or additional syntax. Scalar Functions Scalar functions in SQL statements permit you to refine the answers from queries, apply filters, or restrict the columns of a result set. Figure 2 . Qualifiers, Owners, and Procedures Duplicate names in tables afford an opportunity for confusion, so SQL supports qualified references to columns and tables. SQL dialects frequently use an owner name to qualify a reference to a table.