Database Null Value Support
In an ILE RPG program, you can select one of three different ways of
handling null-capable fields from an externally described database file. This
depends on how the ALWNULL keyword on a control specification
is used (ALWNULL can also be specified as a command parameter):
- ALWNULL(*USRCTL) - read, write, update, and delete records with null values and retrieve and position-to records with null keys.
- ALWNULL(*INPUTONLY) - read records with null values to access the data in the null fields
- ALWNULL(*NO) - do not process records with null values
Note: For a program-described file, a null value in the record
always causes a data mapping error, regardless of the value specified on the
ALWNULL keyword.