wordpress mysql - delete all custom post type
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I've got a wordpress/mysql set up using the 'custom post type' which currently holds about 40,000 rows of data in the wp_posts table of the database.   I'm trying to work on an SQL query that will remove all the rows of a certain custom post type in one go but it keeps telling me I've got a syntax error. The code I'm using is below, apologies if it's simple but SQL is alien to me and I'm struggling to find anything in the forums.

DELETE FROM `wp_posts`
WHERE  `post_type` =  'prefix-numberplates'
LIMIT 0 , 3000

There are ` around wp_posts & post_type but it won't let me style them on here.
Any help is greatly appreciated.

 