Mysql技巧：删除单个表中重复的项
第一步：查寻重复的项及数量

SELECT email,
COUNT(email) AS Num
FROM zhaiduo_table
GROUP BY email
HAVING ( COUNT(email) > 1 )
第二步：根据项目email和数量Num，一个个的删除
DELETE FROM zhaiduo_table WHERE email=’zhaiduo@mail.com’ LIMIT Num-1;