Built-in functions
A built-in function is a predefined function, such as cos() or length(), that the database server provides for use in an SQL expression. The database server supports built-in functions on the built-in data types. For an opaque data type, you must overload the function for the opaque type.
For general information about these built-in functions, see Built-in functions. For information about how to overload a built-in function on an opaque data type, see Built-in functions for opaque data types.