Question

我创建了表stu_dep_det

CREATE TABLE  `stu_dept_cs` (
  `s_d_id` int(10) unsigned NOT NULL auto_increment,
  `stu_name` varchar(15) , `gender` varchar(15) , `address` varchar(15),`reg_no` int(10) ,
  `ex_no` varchar(10) ,
  `mark1` varchar(10) ,
  `mark2` varchar(15) ,
  `mark3` varchar(15) ,
  `total` varchar(15) ,
  `avg` double(2,0),
  PRIMARY KEY  (`s_d_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC AUTO_INCREMENT=8 ;

然后插入值

INSERT INTO `stu_dept_cs` (`s_d_id`, `stu_name`, `gender`, `address`, `reg_no`, `ex_no`, `mark1`, `mark2`, `mark3`, `total`, `avg`) VALUES
(1, 'alex', 'm', 'chennai', 5001, 's1', '70', '90', '95', '255', 85),
(2, 'peter', 'm', 'chennai', 5002, 's1', '80', '70', '90', '240', 80),
(6, 'parv', 'f', 'mumbai', 5003, 's1', '88', '60', '80', '228', 76),
(7, 'basu', 'm', 'kolkatta', 5004, 's1', '85', '95', '56', '236', 79);

我想使用having关键字选择min（avg），并且我使用了以下sql语句

SELECT * FROM stu_dept_cs s  having  min(avg)

是否正确plz写出正确的ans ....

Answer 1

select somecolumn1,somecolumn2
from stu_dept_cs 
group by somecolumn1,somecolumn2,avg
having avg = min(avg)

或

with t1
(select rownumber() over (partition by somecolumn1,somecolumn2 
    order by somecolumn1,somecolumn2,avg asc) as rownum
from stu_dept_cs )
select * from t1 where rownum=1

Answer 2

SELECT t1.* FROM stu_dept_cs t1
LEFT JOIN stu_dept_cs t2
ON t1.avg > t2.avg
WHERE t2.stu_name IS NULL;

如何使用关键字选择最小值

2 个答案: