发现wordpress的wp_postmeta数据库有许多重复的数据以及不需要的数据，今天网上找到解决方法

查询重复数据命令：

SELECT * FROM `wp_postmeta` WHERE (post_id,meta_key) IN ( SELECT post_id,meta_key FROM wp_postmeta GROUP BY post_id,meta_key HAVING COUNT(1) > 1 )

删除数据表中wp_postmeta 中 meta_key中 指定的数据_wp2sinaid命令：

DELETE FROM wp_postmeta WHERE meta_key = '_wp2sinaid';

查询并删除wp_postmeta中重复数据

DELETE FROM wp_postmeta WHERE meta_id IN (
SELECT *
FROM (

SELECT meta_id
FROM wp_postmeta
WHERE (
post_id, meta_key, meta_value
)
IN (

SELECT post_id, meta_key, meta_value
FROM wp_postmeta
GROUP BY post_id, meta_key, meta_value
HAVING COUNT( 1 ) >1
)
AND meta_id NOT
IN (

SELECT MIN( meta_id )
FROM wp_postmeta
GROUP BY post_id, meta_key, meta_value
HAVING COUNT( 1 ) >1
)
) AS stu_repeat_copy
)

注：wp_postmeta是wordpress本来的原表名，如果你在建站的时候有更改的话，那么所有的wp_postmeta都应该改为现在数据表名现有的样子。如你看到的是wp_xxxpostmeta那么你就该改为wp_xxxpostmeta

以上仅作为个人日后使用备用，也相信各位也用得着。