From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ben Morrow <ben@morrow.me.uk>
Cc: jorgemal1960@gmail.com
Cc: pgsql-sql@postgresql.org
Subject: Re: UPDATE query with variable number of OR conditions in WHERE
Date: Thu, 14 Mar 2013 23:15:17 -0400
Message-ID: <19955.1363317317@sss.pgh.pa.us> (raw)
In-Reply-To: <20130314235807.GA81164@anubis.morrow.me.uk>
References: <20130314235807.GA81164@anubis.morrow.me.uk>
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Ben Morrow <ben@morrow.me.uk> writes:
> Quoth jorgemal1960@gmail.com (JORGE MALDONADO):
>> I am building an UPDATE query at run-time and one of the fields I want to
>> include in the WHERE condition may repeat several times, I do not know how
>> many.
>>
>> UPDATE table1
>> SET field1 = "some value"
>> WHERE (field2 = value_1 OR field2 = value_2 OR .....OR field2 = value_n)
>>
>> I build such a query using a programming language and, after that, I
>> execute it. Is this a good approach to build such a query?
> You can use IN for this:
> UPDATE table1
> SET field1 = "some value"
> WHERE field2 IN (value_1, value_2, ...);
IN is definitely better style than a long chain of ORs. Another
possibility is to use = ANY(ARRAY):
UPDATE table1
SET field1 = "some value"
WHERE field2 = ANY (ARRAY[value_1, value_2, ...]);
This is not better than IN as-is (in particular, IN is SQL-standard and
this is not), but it opens the door to treating the array of values as a
single parameter:
UPDATE table1
SET field1 = "some value"
WHERE field2 = ANY ($1::int[]);
(or text[], etc). Now you can build the array client-side and not need
a new statement for each different number of comparison values. If
you're not into prepared statements, this may not excite you, but some
people find it to be a big deal.
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, ben@morrow.me.uk, jorgemal1960@gmail.com
Subject: Re: UPDATE query with variable number of OR conditions in WHERE
In-Reply-To: <19955.1363317317@sss.pgh.pa.us>
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