Re: EVAL and SET equivalents in PostgreSQL

From: Alvaro Herrera <alvherre(at)atentus(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Lynn David Newton <lynn(dot)newton(at)cox(dot)net>, <pgsql-general(at)postgresql(dot)org>
Subject: Re: EVAL and SET equivalents in PostgreSQL
Date: 2002-07-04 03:19:22
Message-ID: Pine.LNX.4.44.0207032303150.7246-100000@cm-lcon-46-187.cm.vtr.net
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Bruce Momjian dijo:

> Sure, use CHECK constraints on the column. That is the ANSI standard
> way.
>
> gender CHAR(1) CHECK (gender IN ('M','F')),

That's the solution for the ENUM MySQL datatype, but the SET datatype
allows one to have multiple values in the column (or that's what I
understood in the original message).

In PostgreSQL, you could use an array to store multiple values. I don't
know if one could set up a CHECK constraint so that every element in a
varchar array is checked against a predefined set. Maybe it can be done
at insertion time using a trigger?

--
Alvaro Herrera (<alvherre[a]atentus.com>)
"Ninguna manada de bestias tiene una voz tan horrible como la humana" (Orual)

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