Sequences are objects, like fields, that you can create and maintain in any OpenEdge database. Unlike fields, sequences reside in a separate database block independent of application tables. The following figure shows the basic relationship between database fields and sequences.
Figure 7. Database fields and sequences comparison
Each sequence has a name and a value, similar to a field. But unlike a field, a sequence also has different schema attributes that determine how the sequence value can change. These include:
Whether the sequence increments or decrements and by what interval
Whether the sequence cycles or terminates
The upper and lower boundaries for sequence values
ABL provides a dedicated set of functions and statements to access and increment sequences strictly according to the defined attributes.
Whether the sequence increments or decrements and by what interval
