DB2 Maestro online Help
Sequences
Sequence is a database object from which multiple users may generate unique integers. You can use sequences to automatically generate primary key values.
When a sequence number is generated, the sequence is incremented, independent of the transaction committing or rolling back. If two users concurrently increment the same sequence, then the sequence numbers each user acquires may have gaps, because sequence numbers are being generated by the other user. One user can never acquire the sequence number generated by another user. Once a sequence value is generated by one user, that user can continue to access that value regardless of whether the sequence is incremented by another user.
New sequences are created within Create Sequence Wizard. In order to run the wizard you should either
| • | select the Object | Create Database Object... main menu item; |
| • | select the Sequence icon in the Create Database Object dialog |
or
| • | select the Sequences list or any object from that list in the explorer tree; |
| • | select the Create New Sequence... item from the popup menu |
or
| • | open the schema in Schema Editor and the Sequences tab there; |
| • | press the Insert key or select the Create New Sequence item from the popup menu (alternatively, you may use the corresponding link of the Navigation Bar). |
To create a new sequence with the same properties as one of the existing sequences has:
| • | select the Object | Duplicate Database Object... main menu item; |
| • | follow the instructions of Duplicate Object Wizard. |
|
Sequences can be edited within Sequence Editor. In order to run the editor you should either
| • | select the sequence for editing in the explorer tree (type the first letters of the sequence name for quick search); |
| • | select the Edit Sequence ... item from the popup menu |
or
| • | open the schema in Schema Editor and the Sequences tab there; |
| • | select the sequence to edit; |
| • | press the Enter key or select the Edit Sequence item from the popup menu (alternatively, you may use the corresponding link of the Navigation Bar). |
|
To drop a sequence:
| • | select the sequence to drop in the explorer tree; |
| • | select the Drop Sequence item from the popup menu |
or
| • | open the schema in Schema Editor and the Sequences tab there; |
| • | select the sequence to drop; |
| • | press the Delete key or select the Drop Sequence item from the popup menu (alternatively, you may use the corresponding link of the Navigation Bar) |
and confirm dropping in the dialog window.
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