On Mar 19, 6:39 pm, Chris <spam_me_...@goaway.com> wrote:
> Robert Klemme wrote:
> > On 19.03.2007 18:11, Chris wrote:
> >> How do I count the unique values in a column in a very large table?
>
> >> I could do this:
>
> >> select mycolumn
> >> from mytable
> >> group by mycolumn;
>
> >> and wait to see how many rows come back. The trouble is that the table
> >> has 75 million rows, and the MySQL Query Browser crashes with an
> >> out-of-memory error after 5 million rows have come back.
>
> >> All is need is a single number: the count. There's got to be a way to
> >> do it in SQL alone.
>
> > count(distinct mycolumn)
>
> > robert
>
> This indicates the right syntax:
>
> http://dev.mysql.com/doc/refman/5.0/...functions.html
>
> But I tried:
>
> select count (distinct session_id) from event_test;
>
> and got:
>
> You have an error in your SQL syntax; check the manual that corresponds
> to your MySQL server version for the right syntax to use near 'distinct
> session_id) from event_test at line 1.
>
> The table and the column name is correct. What am I doing wrong?

When it says 'near', it nearly always means 'immediately to the left
of'!

Try removing the space between count and (