How can I rewrite this query so as to avoid the error: You can't specify target table for update in FROM clause

update websites set master = 2 where url = select url from websites where id = 12;

Apparently mysql won't allow you t开发者_运维技巧o run a select query on table you're updating.

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Put it into a derived table. This gets materialised into a temp table and gets around the restriction.

update websites
set    master = 2
where  url in (select url
               from   (select url
                       from   websites
                       where  id = 12) t);  

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update websites set master = 2 where url in (select w2.url from websites w2 where w2.id = 12);