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Subject: Re: Like Command returning wrong result set
From: Christophe Pettus <xof@thebuild.com>
In-Reply-To: 
 <CH0PR12MB5105EEAFE0AF3085B4F1095FD2F29@CH0PR12MB5105.namprd12.prod.outlook.com>
Date: Thu, 5 Aug 2021 07:05:13 -0700
Cc: "pgsql-sql@postgresql.org" <pgsql-sql@postgresql.org>
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Message-Id: <595A741D-8D12-4FB8-8794-28D3319EE2CD@thebuild.com>
References: 
 <CH0PR12MB5105EEAFE0AF3085B4F1095FD2F29@CH0PR12MB5105.namprd12.prod.outlook.com>
To: "Tchouante, Merlin" <mtchouan@umaryland.edu>
Archived-At: 
 <https://www.postgresql.org/message-id/595A741D-8D12-4FB8-8794-28D3319EE2CD%40thebuild.com>
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> On Aug 5, 2021, at 07:00, Tchouante, Merlin <mtchouan@umaryland.edu> =
wrote:
>=20
> Hello group,
> =20
> I=E2=80=99m writing a script and a bit confused on the results with =
the like command.
> =20
> gm.title like 'CP_%'
> =20
> The above command gives me records with titles like CP_40, CP_2, =
CP_23, etc.
> =20
> gm.title like '%_CT'

Somewhat confusingly, '_' is the single-character wildcard for SQL's =
LIKE operation:

xof=3D# SELECT 'A' LIKE '_';
 ?column?=20
----------
 t
(1 row)

You can escape it to search for it literally:

xof=3D# SELECT '_' LIKE '\_';
 ?column?=20
----------
 t
(1 row)

xof=3D# SELECT 'A' LIKE '\_';
 ?column?=20
----------
 f
(1 row)