Extending Informix-Universal Server: Data Types
Chapter 2: Extending an Operation
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An operation is a task that INFORMIX-Universal Server performs on one or more values. Universal Server provides the following types of SQL-invoked functions that provide operations within SQL statements:
Operator symbols (such as +, -, /, and *) and their associated operator functions
Built-in functions such as
cos()
and
abs()
Aggregate functions such as
SUM
and
AVG
End-user routines
These functions that Universal Server provides handle the built-in data types. For user-defined data type to use any of these functions, you can write a new function that has the same name but that accepts the user-defined data type in its parameter list.
The property called
routine overloading
allows you to create a user-defined function whose name is already defined in the database but whose parameter list is different. All functions with the same name have the same functionality, but they operate on different data types. Universal Server uses
routine resolution
to determine which function to execute, based on the data types of the arguments for the function. For more information on routine overloading and routine resolution, see Chapter 1 of
Extending INFORMIX-Universal Server: User-Defined Routines
.
Extending Informix-Universal Server: Data Types
, version 9.1
Copyright © 1998, Informix Software, Inc. All rights reserved.
