[TYPO3-dev] Use of subqueries

[Martin Kutschker]

Rik Willems schrieb:
> Hi Masi,
> 
> What exactly do you mean with EXPLAIN?

Mysql will tell you how it executes a query if you put an EXPLAIN before it.

Fire up phpMyAdmin and execute for example this statement:

EXPLAIN SELECT * FROM pages p LEFT JOIN pages_language_overlay plo ON (p.uid=plo.pid)

EXPLAIN helps a lot to check if your queries and indices are efficient! Mysql may surprise you how
it uses your indices and in what order it executes the joins.

See the Mysql docs for more information.

Masi