Sorry for taking varchar(4) as an example, What I want urgently is how to make a constraint of fixed length of a numeric data,
that you can only input data like 23.45, and if you input the data like 2.45, 23.4356, 233.45, you will get a warning
message from postgresql.
I think expr will do the job, but are there any simpler ways to do it in postgresql?
Requiring a fixed length, and not an amount range is unusual. That the only way to do it is to consider the input as text and use a regular _expression_ is understandable.
David J.
