mysql取差集、交集、并集博客分类： Mysql数据库 需求：从两个不同的结果集（一个是子集，一个是父集），字段为电话号码phone_number,找出父集中缺少的电话号码，以明确用户身份。 结合网上资料，整理sql如下： //mysql取差集 Java代码  收藏代码select num FROM  (    select u.code_sn as id,u.phone_number as num from t1 b  left join t2 u  on b.from_user=u.code_sn  where b.to_account='1000' and b.json_info like '%09月份%'    union all    select u.code_sn as id,u.phone_number as num from t3 o  left join t2 u  on o.buyer_code_sn=u.code_sn  where o.seller_account_code_sn='1000' and o.json_info like '%09月份%'     )t3  group by num having count(num)=1  //mysql取交集 Java代码  收藏代码select num FROM  (    select u.code_sn as id,u.phone_number as num from t1 b  left join t2 u  on b.from_user=u.code_sn  where b.to_account='1000' and b.json_info like '%09月份%'    union all    select u.code_sn as id,u.phone_number as num from t1 o  left join t2 u  on o.buyer_code_sn=u.code_sn  where o.seller_account_code_sn='1000' and o.json_info like '%09月份%'     )t3  group by num having count(num)=2  //mysql取并集 Java代码  收藏代码select num FROM  (    select u.code_sn as id,u.phone_number as num from t1 b  left join t2 u  on b.from_user=u.code_sn  where b.to_account='1000' and b.json_info like '%09月份%'    union all    select u.code_sn as id,u.phone_number as num from t1 o  left join t2 u  on o.buyer_code_sn=u.code_sn  where o.seller_account_code_sn='1000' and o.json_info like '%09月份%'     )t3