Function Instance Definitions
A function instance definition defines the use of a function or operator in a particular context. Because the same function can be used differently with different data types, each instance of use must be defined. For example, different function instances exist for the + operator: one to add integers, one to concatenate text, one to add money, and so on.
When you are defining a new data type, you must also define a function instance for each function or operator that you use with the new data type. If, for example, you want to add two values of the new data type, you must first define a function instance for the + operator used with the new data types. When you define a new SQL function, you must define a function instance for its use with each data type with which it is used.
The definition of a function instance is composed of:
• Function instance identifier (a 2-byte integer)
• Function instance complement identifier (if this instance is a comparison)
• Operator or function identifier for which this is an instance
• Operator type
• Function instance status flags
• Number of arguments and their data types
• Workspace length
• Data type of the result
• Length of the result
• Address of the routine that performs the instance
Note: Object Management Extension does not allow you to redefine the use of the standard operators with existing SQL data types and functions. If you try to do this, you do not receive an error, but the code is ignored.
Last modified date: 08/14/2024