On 06/11/2015 07:17 AM, Marc Mamin wrote:
That's the point. * has no meaning without FROM
But COUNT(*)
does have meaning - it means "the number of rows".
which rows? :-)
To follow up on the post from Chris Mair:
test=> select count(*), 'foo';
count | ?column?
-------+----------
1 | foo
See also:
http://www.postgresql.org/docs/9.4/interactive/functions-aggregate.html
count(*) bigint number of input rows
It's not counting the number of columns in the row, so postgres doesn't need to know what columns exist in the row to return a row count.
Geoff
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Adrian Klaver
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