Creating a sequence is probably the simplest thing to do. By clicking New Sequence, the following window is displayed.
Figure 8: Creating a Sequence
The first step is to define the name of the sequence. In this case, I have a table named employees so it only makes sense to name the sequence seq_employees. While this is only a recommendation, you should use some sort of naming standard with your database objects. Next, define the type, values, and options of the sequence. If you are not sure what options to select, please refer to the following.
Allow cycle: Specifies whether the sequence generator will cycle back to MINVALUE from MAXVALUE when MAXVALUE is met. For sequences providing key values, it is probably not the best idea to cycle back.
Order values: This guarantees that sequence numbers are generated in order of the request.
Cache: The cache option specifies how many sequence values will be stored in memory for faster access. No cache means that none of the sequence values will be stored in memory.