View Full Version : count (*) from (select ....)
04-05-2009, 07:52 AM
SELECT Count(*) FROM (SELECT * FROM table)
--> Every derived table must have its own alias
How to do this ?
huh, cant tell why now works.
SELECT Count(*) FROM (SELECT * FROM table) as Z
04-05-2009, 08:10 AM
As the message said, your DERIVED TABLE (which is what that
SELECT * FROM table
is) needed an alias. Yes as Z is indeed an alias.
Explain to us why you thought you *needed* a derived table????
Why didn't you just code
SELECT COUNT(*) FROM table
04-05-2009, 08:52 AM
(SELECT * FROM table) is just a demo
real sql isn't simple as this, in fact it return something like this, forinstance 1 count column which is already grouped . including bunch of joins, and one complicated tip from you Old pedant :-).... -->
and what I need is count of resulting rows, i.e. 4
04-05-2009, 09:07 PM
Okay, makes sense. But anyway, I guess as you noted, all you needed was the AS clause.
This is, by the by, a MySQL requirement. SQL Server doesn't require it, for example.
Yet another of the quirky differences between different dialects of SQL.
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