On Wed, 2005-10-19 at 15:25 +0100, Ledina Hido wrote: > First of all, is there any way of limiting the number of rows in a > table, referencing to the same element of another table? For example, > force a manager not to have more than 10 employees under his control. > In a way this can be seen as checking the multiplicity of the > relation between the two tables. I know one way would be using > triggers, but I was wondering if there was a way of specifying this > when the table is constructed. That's a lack of function within the SQL standard and PostgreSQL doesn't implement that as an extension. XML Schema allows you to define minoccurs and maxoccurs, but not the SQL:2003 standard. It would be very cool if it did, I grant you. You have to do this yourself via a trigger. Just make sure you create an index on the columns and you'll be fine - apart from the extra cost of inserting rows, so keep maxoccurs small. Best Regards, Simon Riggs ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
