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[nycphp-talk] MySQL: count()children on 2 related tables in 1 query

Dan Cech dcech at phpwerx.net
Tue Jan 4 16:02:05 EST 2011


Sorry, forgot the ON clauses:

SELECT parent.id, parent.someColumn, c1.cnt, c2.cnt
FROM parent
LEFT JOIN (
     SELECT child_table_1.parent_id,count(child_table_1.id) as cnt
     FROM child_table_1
     GROUP BY child_table_1.parent_id
) AS c1 ON c1.parent_id=parent.id
LEFT JOIN (
     SELECT child_table_2.parent_id,count(child_table_2.id) as cnt
     FROM child_table_2
     GROUP BY child_table_2.parent_id
) AS c2 ON c2.parent_id=parent.id

Dan



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