CAST doesn't work :-(

Hi.

I read in Momjian's book that to change the CHAR length of a column in a table (from 30 -> 40) lets say, i'm to use the CAST command (pg 93). The fact is that the Posgres User's manual has nothing about cast and psql doesn't understand this command :-(((((((

Anyone can tell me how to ajust a CHAR length in a table column? I found out that some email exceed 30 digits now i can't insert them and don't want to start from scratch.

Thanks.

--
Antonio Gennarini
Crecchio, CH - ITALY
-----------------------------------
Earth Science student at University "G. D'Annunzio".
Join th GNU generation, start from LINUX.