Built-in functions and operator functions
Built-in functions perform arithmetic and other basic operations when included in SQL statements. Operator functions are built-in functions that are bound to operator symbols.
For example, the plus() function is bound to the + operator. Some of the arithmetic functions take a single argument, such as the root() function, which calculates the square root of its argument; others take two arguments, such as the pow() function, which raises one argument to the power of the second.
When you overload a built-in or operator function, you must specify
what the function does and what it returns. For example, if you overload
the plus() function on a row type, you can choose
to:
- add the respective field values and return a row type with the same number of fields as the input row types
- return a row type that contains all the fields of the first input row type followed by all the fields of the second input row type
There are also built-in functions that do not take arguments and that you cannot overload, such as the today() function, which returns the current date and time.
For more information, see the Informix® User-Defined Routines and Data Types Developer's Guide.