mysql statement with nested SELECT - how to improve performance

Posted by ernie on Stack Overflow See other posts from Stack Overflow or by ernie
Published on 2010-04-22T10:53:31Z Indexed on 2010/04/22 11:43 UTC
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mysql

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Performance

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sql

This statement appears inefficient because only one one out of 10 records are selected and only 1 of 100 entries contain comments.

What can I do to improve it ?

$query = "SELECT 
A,B,C,  
(SELECT COUNT(*)
    FROM comments
    WHERE comments.nid = header_file.nid) 
    as my_comment_count
FROM  header_file
Where A = 'admin' "

edit: I want header records even if no comments are found.

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