What is operator function?

Answer 1

An operator function implements a particular operator symbol. The database server provides special SQL-invoked functions, called operator functions, that implement operators. An operator function processes one to three arguments and returns a value. When an SQL statement contains an operator, the database server automatically invokes the associated operator function. The association between an operator and an operator function is called operator binding. You can overload an operator function to provide the operator for a UDT. The SQL user can then use the operator with the UDT as well as with the built-in data types. When an SQL statement contains an operator, the database server automatically invokes the associated operator function.