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Thread: Error with DISTINCT

Error with DISTINCT

From
Jerome Raupach
Date:
testdb=#SELECT DISTINCT table_2.f1, table_1.f2, '2000-08-22' AS
testdb-#date FROM table_1, table_2 WHERE table_1.f1 = table_2.f1;
ERROR:  Unable to identify an ordering operator '<' for type 'unknown'       Use an explicit ordering operator or
modifythe query
 

I must execute this query :

testdb=#SELECT table_2.f1, table_1.f2, '2000-08-22' AS date FROM
testdb-#table_1, table_2 WHERE table_1.f1 = table_2.f1 GROUP BY
testdb-#table_2.f1, table_1.f2;

Is it a bug ?
Thanks in advance.

Jerome.

Re: Error with DISTINCT

From
Tom Lane
Date:
Jerome Raupach <jraupach@intelcom.fr> writes:
> testdb=#SELECT DISTINCT table_2.f1, table_1.f2, '2000-08-22' AS
> testdb-#date FROM table_1, table_2 WHERE table_1.f1 = table_2.f1;
> ERROR:  Unable to identify an ordering operator '<' for type 'unknown'
>         Use an explicit ordering operator or modify the query

> Is it a bug ?

No, I don't think so.  The system has no way to intuit what datatype
you consider '2000-08-22' to be.

SELECT DISTINCT table_2.f1, table_1.f2, '2000-08-22'::date ...

would work.
        regards, tom lane

Re: Error with DISTINCT

From
Jie Liang
Date:
Hi,

try this:
testdb=#SELECT DISTINCT table_2.f1, table_1.f2, date('2000-08-22') AS
testdb-#date FROM table_1, table_2 WHERE table_1.f1 = table_2.f1;

Jerome Raupach wrote:

> testdb=#SELECT DISTINCT table_2.f1, table_1.f2, '2000-08-22' AS
> testdb-#date FROM table_1, table_2 WHERE table_1.f1 = table_2.f1;
> ERROR:  Unable to identify an ordering operator '<' for type 'unknown'
>         Use an explicit ordering operator or modify the query
>
> I must execute this query :
>
> testdb=#SELECT table_2.f1, table_1.f2, '2000-08-22' AS date FROM
> testdb-#table_1, table_2 WHERE table_1.f1 = table_2.f1 GROUP BY
> testdb-#table_2.f1, table_1.f2;
>
> Is it a bug ?
> Thanks in advance.
>
> Jerome.

--
Jie LIANG

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