A variable is a program element that can hold volatile data. The
following list summarizes variables usage:
- Variables are declared in programs with the DEFINE
instruction.
- After definition, variables get default values according their
type.
- The scope of a variable can be global, local to a module, or local
to a function.
- When defined at the module level, a variable can be declare it as
PRIVATE or PUBLIC.
- You can define structured variables with records, and with arrays.
- Default values (or NULL) can be assigned with the INITIALIZE instruction.
- Direct value assignment is done with the LET instruction.
- Database validation rules can be applied with the VALIDATE instruction.
- Variables can be used as SQL parameters or fetch buffers in SQL
statements.
- Interactive instructions use program variables as model to hold
the data.