Re: How to restrict

Ron <ronljohnsonjr@xxxxxxxxx> · Tue, 26 Feb 2019 09:24:22 -0600



    On 2/26/19 9:11 AM, Campbell, Lance wrote:

    
        PostgreSQL
            10.x
         
        What is the
            best way to restrict the values on a text field to make sure
            they only contain particular values:  Example:  The field
            “type” can only contain the values of “X”, “Y” and “Z”. 
            Would a trigger be the best strategy?  Or is there a special
            SQL type I should use in this particular case?  

          
    Use either a CHECK constraint or FOREIGN KEY.

    
    For just a few items, understanding that you must drop and
    recreate the constraint to modify it.
    http://www.postgresqltutorial.com/postgresql-check-constraint/

    CREATE TABLE foo 

    (

        bar VARCHAR(20) CHECK (bar IN ('X', 'Y', 'Z'))

    );

    
    For more items, and simpler additions:
    http://www.postgresqltutorial.com/postgresql-foreign-key/

    
    -- 

      Angular momentum makes the world go 'round.