Grzegorz Jaśkiewicz wrote:
On Mon, Dec 8, 2008 at 10:19 PM, Madison Kelly <linux@xxxxxxxxxxx> wrote:
Hi all,
I've got a table that I am trying to SELECT DISTINCT on one column and
ORDER BY on a second column, but am getting the error:
SELECT DISTINCT ON expressions must match initial ORDER BY expressions
try
SELECT distinct, array_accum(bar) FROM table WHERE bar < '2008-12-07
16:32:46' AND tbl_id=153 ORDER BY bar LIMIT 1;
or even, when you change bar to proper type - that is, timestamp
SELECT distinct foo, min(bar) as minbar, max(bar) as maxbar FROM
table WHERE bar < '2008-12-07
16:32:46' AND tbl_id=153 ORDER BY bar LIMIT 1;
etc.
Trick, is to use aggregate on other value(s).
HTH
Well shoot, I didn't realize I had the 'text' where I should have used
'timestamp'. >_<
I updated the column, but it took me some fiddling (on a test box!) to
sort out the proper command. In case it helps someone else, here was the
error I was getting when I tried ALTER without USING:
ALTER TABLE table ALTER foo TYPE TIMESTAMP WITHOUT TIME ZONE;
ERROR: column "foo" cannot be cast to type "pg_catalog.timestamp"
The syntax I needed was:
ALTER TABLE table ALTER foo TYPE TIMESTAMP WITHOUT TIME ZONE USING CAST
(foo AS TIMESTAMP);
I know it's a little off-topic, but maybe it'll help someone searching
someday. :)
When I try to use:
SELECT distinct foo, min(bar) as minbar, max(bar) as maxbar FROM table
WHERE bar < '2008-12-07 16:32:46' AND tbl_id=153 ORDER BY bar LIMIT 1;
I get the error:
ERROR: column "table.foo" must appear in the GROUP BY clause or be used
in an aggregate function
Already a very big help though, thanks!
Madi
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