数据库SQL查询语句的几个问题,求解答

发布网友发布时间：2022-04-29 04:46

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共4个回答

懂视网时间：2022-04-11 09:49

类型 varchar

查询语句 select * from tab_1 where version =(select max(version) from tab_1)

此时查询的版本当版本在1-9时数据正常当版本超过10 就一直查询为9

解决方法

select max(cast(version as UNSIGNED INTEGER)) from tab_1

原因：查询varchar 9 10 11 中 9 最大（这么说很简明了。。。）只要将格式进行转换便可正常查询

sql语句查询中常见的小问题

标签：常见 sel var bsp where version har ros tab

热心网友时间：2022-04-11 06:57

select cno,cn from COURSE c where cno exists(
select distinct s.cno from SC s, TEACHERS t where s.tno = t.tno and t.tno='05')

select sno,sn from STUDENTS where dept="外语系"age <select min(age) from STUDENTS where dept='信息系'

union

select sno,sn from STUDENTS where dept="计算机系"age <select min(age) from STUDENTS where dept='信息系'

union ...

select cno,num from COUTSE c inner join(select cno,count(cno) as num from SC
group by cno
having count(cno) > 2) b

on c.cno = b.cno

热心网友时间：2022-04-11 08:15

1.select cno,cn from sc s
inner join course c
on s.cno = c.cno
where s.tno = '05'
2.
select sno,sn from students
where dept <> '信息系'
and age <
(select min(age) from students
where dept = ‘信息系')
3
select cno,count(sno)
from SC
where cno in
(
select cno from SC
group by cno
having count(sno) > 2
)
group by cno

热心网友时间：2022-04-11 09:50

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