Question

… for strings, it’s easy… LENGTH(attribute), but for ints, LENGTH always returns “4” for ints, “8” for bigints, etc etc.

So given a statement like this:

create table EMPLOYEE (employeeno bigint NOT NULL PRIMARY KEY);

How could I add a CHECK clause that’ll check to see whether an inserted employeeno is exactly 6 digits?

Answer 1

Use a check constraint to check for val >= 100000 and val <= 999999.

If you need to, you can change this to val >= 0 and val <= 999999. Note that int types do not contain any information about leading zeroes, so that information is already lost by the time it hits the database.