On 19 Mar 2008, at 14:53, tedd wrote:
At 10:35 AM -0400 3/19/08, Nathan Nobbe wrote:
On Wed, Mar 19, 2008 at 9:42 AM, Andrew Ballard <[EMAIL PROTECTED]> wrote:

That works; I'm just wondering why you went with a count on an 'ID' column
rather than COUNT(*).


ouch, it looks like im horribly wrong :O
mysql> select count(*) from table;
+----------+
| count(*) |
+----------+
|   361724 |
+----------+
1 row in set (0.90 sec)

mysql> select count(id) from table;
+------------+
| count(did) |
+------------+
|     361724 |
+------------+
1 row in set (4.56 sec)

-nathan

That surprised me as well.

I thought that (*) meant "look up everything" and would have figured that (id) would have been quicker.

Using count(*) can be optimised, as can count(1) which is what I usually use. Using a specific field is harder to optimise.

-Stut

--
http://stut.net/

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