"Anton Melser" <melser(dot)anton(at)gmail(dot)com> writes:
> I am trying to understand the function substring.
You haven't actually said anything that sounded surprising; and in any
case, without seeing the data being operated on, we can't comment much
on what's happening. I will note that '=([0-9]*)' is going to match
to the *first* "=" in the string, whether there happen to be any digits
after it or not, because the *-construct can match zero characters.
regards, tom lane