关于php数据库的问题

Question

怎么查询重复的数据，以及怎么根据表中数据没有重复的去跟另一个表做更新操作，请问sql语句该怎么写呢，感谢

Answer 1

update sdb_b2c_goods,sdb_b2c_cat_alias 
set sdb_b2c_goods.cat_id = sdb_b2c_cat_alias.cat_id 
where sdb_b2c_goods.category_en=sdb_b2c_cat_alias.alias and sdb_b2c_goods.category_en in (
    SELECT alias  FROM (
    SELECT COUNT(alias) AS num, alias FROM sdb_b2c_cat_alias GROUP BY alias ) AS tmptable   WHERE tmptable.num =1
)

经过测试可用