RE: counting distinct rows on more than one column

SELECT count(*) FROM (SELECT DISTINCT a, b FROM t) AS t2;

should give you what you want.

MikeA

>> -----Original Message-----
>> From: Dirk Lutzebaeck [mailto:lutzeb(at)aeccom(dot)com]
>> Sent: 28 March 2001 16:11
>> To: pgsql-sql(at)postgresql(dot)org
>> Subject: [SQL] counting distinct rows on more than one column
>>
>>
>>
>> Hi,
>>
>> on 7.0.3 want to COUNT
>>
>> SELECT DISTINCT a,b FROM t;
>>
>> I can't find a solution because any combination with
>> count with more than one column gives syntax errors.
>>
>> One solution would be to set a view:
>>
>> CREATE VIEW v AS SELECT DISTINCT a,b FROM t;
>>
>> and then
>>
>> SELECT count(a) FROM v
>>
>> but views don't support distinct in v7.0.3
>>
>> Ok I could use a temporary table but my select distinct tends to give
>> large results.
>>
>> Any clues?
>>
>> Dirk
>>
>>
>>
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