Question

I’m fairly proficient in mySQL and MSSQL, but I’m just getting started with postgres. I’m sure this is a simple issue, so to be brief:

SQL error:

ERROR:  column "incidents.open_date" must appear in the GROUP BY clause or be used in an aggregate function

In statement:
SELECT date(open_date), COUNT(*)
FROM incidents
GROUP BY 1
ORDER BY open_date

The type for open_date is timestamp with time zone, and I get the same results if I use GROUP BY date(open_date).

I’ve tried going over the postgres docs and some examples online, but everything seems to indicate that this should be valid.

Answer 1

The problem is with the unadorned open_date in the ORDER BY clause.

This should do it:

  SELECT date(open_date), COUNT(*)
    FROM incidents
GROUP BY date(open_date)
ORDER BY date(open_date);

This would also work (though I prefer not to use integers to refer to columns for maintenance reasons):

  SELECT date(open_date), COUNT(*)
    FROM incidents
GROUP BY 1
ORDER BY 1;