Generating IDs can be broken down into two cases:
- perform an action before the insert (call a sequence, generator or pull the next value from a table)
- perform an action after the insert (generally by asking the driver for a property -- 'mysql_insertid' -- or calling another statement to fetch a value -- 'SELECT @@IDENTITY')
So the easiest way I've found to do this is create pre/post actions for the insert and register certain generative capabilities with certain drivers. (This is how we do it in SPOPS.) If you're using PostgreSQL/Oracle/FirebirdSQL you need to fetch the next value from a sequence/generator. And if you're using MySQL/Sybase you need to create an INSERT using all fields except the ID field, then get the ID afterwards.
IME trying to be portable with something like this tends to get you in trouble, since most people already have some scheme for doing this that works quickly, atomically and reliably.
Best of luck,
Chris
M-x auto-bs-mode
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