Like built-in operators, user-defined operators take a set of operands as input and return a result. However, you create them with the CREATE OPERATOR statement, and they are identified by user-defined names. They reside in the same namespace as tables, views, types, and standalone functions.

After you have defined a new operator, you can use it in SQL statements like any other built-in operator. For example, you can use user-defined operators in the select list of a SELECT statement, the condition of a WHERE clause, or in ORDER BY clauses and GROUP BY clauses. However, you must have EXECUTE privilege on the operator to do so, because it is a user-defined object.