Is it possible to force values of a column to be lowercase

Question

I'm working with PostgreSQL 9.3.

I have a table with a varchar column that I always want to be filled with lowercase strings.

I could use the Postgres lower function before saving my values, but is there instead a way to define this column as a lowercase column?

Answer 1

You can accomplish this with a simple check in the column:

create table lower_field (
    field1 varchar check (field1 = lower(field1))
    );