[thelist] MySQL query with two left joins

Gary McPherson genyus at ingenyus.net
Wed Jul 2 08:55:21 CDT 2003


> > I'm not sure if MySQL supports the use of a sub-select in 
> the SELECT 
> > clause, but if it does, can you give me an idea of how to do this?
> 
> SELECT c.CategoryID,
>            c.Title,
> (SELECT Count(*)
> FROM jn_DocumentCategories dc
> WHERE dc.CategoryID = c.CategoryID) AS documents_in_category 
> FROM Categories c WHERE 2 IN (c.ParentCategoryID, c.CategoryID)

Subqueries like this are only supported in MySQL 4.1+. If an older
version is installed, you either have to upgrade or figure out a
workaround (which I believe I may be able to do with a little
headscratching).

Gary




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