User-Defined Operators

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 names. They reside in the same namespace as tables, views, types, and standalone functions.

Once 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.

For example, if you define an operator includes, which takes as input a text column and a keyword and returns 1 if the row contains the specified keyword, you can then write the following SQL query:

SELECT * FROM product_descriptions 
   WHERE includes (translated_description, 'Oracle and UNIX') = 1;