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From: Gary Stainburn <gary.stainburn@ringways.co.uk>
Organization: Ringways Garages Ltd
To: pgsql-sql@postgresql.org
Subject: unique value - trigger?
Date: Thu, 17 Jul 2003 12:56:52 +0100
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Message-Id: <200307171256.52098.gary.stainburn@ringways.co.uk>

Hi folks,

I'm back with my lnumbers table again.

nymr=# \d lnumbers
               Table "lnumbers"
  Column   |         Type          | Modifiers
-----------+-----------------------+-----------
 lnid      | integer               | not null
 lnumber   | character varying(10) | not null
 lncurrent | boolean               |
Primary key: lnumbers_pkey
Triggers: RI_ConstraintTrigger_7575462

While each loco can have a number of different numbers, only one can be 
current at any one time.

I want to make it so that if I set lncurrent to true for one row, any existing 
true rows are set to false.

I'm guessing that I need to create a trigger to be actioned after an insert or 
update which would update set lncurrent=false where lnid not = <current lnid> 
but I can't seem to sus it put.

-- 
Gary Stainburn
 
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