Luke Taylor wrote:
> Isn't it rather risky using MAX to obtain the next primary key, as
> there could be multiple threads creating new entities, and two or more
> of them could obtain the same value for MAX and attempt to use the same
> primary key?
If done outside a transaction, you could risk
the above scenario. But if the "SELECT MAX(...) ..."
and the "CREATE ..." is done in the same transaction,
the transaction isolation ensures that this cannot
happen.
> The best way I'm aware of is to use a DB sequence, but
> this involves proprietary SQL.
Yes, sequences are better, but not all databases support
them.
Best Regards,
Ole Husgaard.
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