Re: What is the postgres version of mysql's "ON DUPLICATE KEY"

Pierre-Frédéric Caillaud wrote:
> > INSERT INTO related_products (product_id,related_product_id)
> > SELECT 1, 2 WHERE NOT EXISTS (SELECT 1
> > FROM
> > related_products
> > WHERE
> > product_id = 1 AND related_product_id = 2)
>
> Should not the SELECT be FOR UPDATE ?
> because if no insert is done, the OP wanted to UPDATE the row, so it
> should not be deleted by another transaction in-between...
>
> Can the above query fail if another transaction inserts a row
> between the SELECT and the INSERT or postgres guarantee that this
> won't happen ?

There is no "between" a single statement.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/