7.3 Using Directives
Directives are optional comments that you can place into an FD in your COBOL source code
to control how the data dictionary is built. By controlling how data dictionaries are built, you can guide the way AcuODBC maps COBOL records to application
data fields.
Directives enable you to:
- specify a column name to be used in place of a COBOL field name.
- map elementary items of a group item together into a single column.
- cause numeric COBOL data to be treated as a text string in the AcuODBC
"virtual" database.
- cause the fields from a specific record in a file to appear in the database table (rather than just the fields from
the largest record).
- give a name to the data dictionary file itself.
Directives are always placed within a COBOL FD. They do not affect Procedure Division I/O statements, and they do not change your COBOL fields in any way. Rather, they guide the building of the
data dictionaries, giving you a measure of control over the way COBOL data is mapped to data fields in your Windows application.
Remember: Each field in the Windows application must correspond to a data item in your
COBOL FD or XFD. To ensure that this is the case, you may need use the NAME directive to add
fields to the data dictionary.
Data dictionaries may be built directly from your source code with no
directives if the compiler's default mapping rules are sufficient for your situation.
If you would like to override the default mapping behavior, or map a field to a
different name, then you would add directives to your COBOL code.
More:
7.3.1 Syntax
7.3.2 AcuODBC Hidden Directive
7.3.3 AcuODBC Read-Only Directive
7.3.4 Date Directive
7.3.5 File Directive
7.3.6 Name Directive
7.3.7 Numeric Directive
7.3.8 Use Group Directive
7.3.9 When Directive