ABF and 4GL
You can develop forms-based applications that access Ingres databases with ABF without using 4GL. For many purposes, Query-By-Forms (QBF) frames and report frames are sufficient. However, for customized frames (such as the start frame), for specialized processing, and for procedures, you must write 4GL code.
4GL is the language for implementing menu operations and other activations. It allows you to control the user's movement among the frames and procedures of an ABF application. It allows you to associate specific operations with each frame to control the operation of the form. Because the form is the input and output medium for a forms-based application, a large part of any forms-based application involves operations that get data from, and display data on, the form. 4GL makes these interactions easy to specify.
Use 4GL to:
• Define custom processing steps for the application.
• Design the overall flow of an application in a series of consistent, easy-to-use menus.
• Fine tune an application by indicating what happens when the application user chooses a menu operation, presses a key, or tries to leave a particular field.
• Specify operations to query and update data in the database.
• Perform selective processing on table fields.
• Perform conditional processing, such as movement from field to field depending on the application user's data entry.
• Call other frames, 4GL procedures, Third Generation Language (3GL) procedures, Ingres tools, or the operating system.
• Pass the result of a query or calculation to another frame.
• Use local variables for calculation or data that the application user does not see.
• Carry out multi-row queries with submenus.
• Create entry forms.
• Perform functions such as clearing the screen, displaying error messages, or causing the terminal to beep.
• Allow for runtime data input.