Sequences are a way of offering unique IDs for data rows. If you
do most of your work with e.g. MySQL, think of sequences as
another way of doing AUTO_INCREMENT.
It's quite simple, first you
request an ID, and then you insert that value in the ID field of
the new row you're creating. You can have more than one sequence
for all your tables, just be sure that you always use the same
sequence for any particular table. To get the value of this
unique ID use
, if a sequence doesn't
exists, it will be created automaticlly.
Example 33-1. Using a sequence
$id = $db->nextId('mySequence');
// Use the ID in your INSERT query
$res = $db->query("INSERT INTO myTable (id,text) VALUES ($id,'foo')");