分别创建了两个临时表，并按不同的字段作查询示例：
create table table1 (id int, ip varchar(15), city char(20)); insert into table1 values(1, '127.0.0.1', '深圳') ;insert into table1 values(2, '127.0.0.2', '广州') ;insert into table1 values(3, '127.0.0.2', '广州') ;insert into table1 values(4, '127.0.0.2', '广州') ;insert into table1 values(5, '127.0.0.2', '北京') ;insert into table1 values(6, '127.0.0.4', '上海') ;insert into table1 values(7, '127.0.0.4', '上海') ;insert into table1 values(8, '127.0.0.4', '上海') ;insert into table1 values(9, '127.0.0.7', '未知'); -- 按字段IP查询 select * from table1 where id in -- 检索重复ip的纪录 (select min(id) from table1 where ip in -- 求重复ip的其中一个id (select ip from table1 group by ip having count(1) >= 1) -- 取出重复的ip group by ip ) ;
返回结果：
1 1 127.0.0.1 深圳 2 2 127.0.0.2 广州 3 6 127.0.0.4 上海 4 9 127.0.0.7 未知
create table table2 (id int, ip varchar(15), city char(20)); insert into table2 values( 1, '127.0.0.1', '深圳') ;insert into table2 values( 2, '127.0.0.2', '广州') ;insert into table2 values( 3, '127.0.0.2', '广州') ;insert into table2 values( 4, '127.0.0.3', '北京') ;insert into table2 values( 5, '127.0.0.3', '北京') ;insert into table2 values( 6, '127.0.0.4', '上海') ;insert into table2 values( 7, '127.0.0.4', '上海') ;insert into table2 values( 8, '127.0.0.4', '上海') ;insert into table2 values( 9, '127.0.0.7', '未知');
-- 按字段city查询 select * from table1 where id in -- 检索重复city的纪录 (select min(id) from table1 where city in -- 求重复city的其中一个id (select city from table1 group by city having count(1) >= 1) -- 取出重复的city group by city );
返回结果：
1 1 127.0.0.1 深圳 2 2 127.0.0.2 广州 3 4 127.0.0.3 北京 4 6 127.0.0.4 上海 5 9 127.0.0.7 未知