In Postgres, how do you restrict possible values for a particular column?

Question

I want to create a column element_type in a table (called discussion) that allows the text values \"lesson\" or \"quiz\" but will generate an error if

Answer 1

A shorcut syntax is :

ALTER TABLE distributors  
   ADD CONSTRAINT check_types 
   CHECK (element_type IN ('lesson', 'quiz') );

This translates automaticolly to :

CONSTRAINT check_types CHECK (element_type::text = ANY (ARRAY['lesson'::character varying, 'quiz'::character varying) )

Enjoy ;-)