mysql试题sql求平均值

蓝和晓1839数据库题目,写出解决下列问题的代码(SQL) -
甫司青13475116281 ______ 1、Select 学生.*,isnull(总订购.总数,0) from 学生 left outer join (select 学号,sum(数量) as 总数 from 订购 group by 学号) as 总订购 on 学生.学号=总订购.学号2、Select 学生.*,isnull(总订购.金额,0) as 应缴书费 from 学生 left outer join ...

蓝和晓1839Mysql数据库求一个sql语句 -
甫司青13475116281 ______ 如果B表已经存在:INSERT INTO B (Num,type2,type1,caozuo....) SELECT Num,type2,type1,caozuo.... FROM A 如果B表不存在:SELECT * INTO B FROM A

蓝和晓1839一道关于SQL数据库的题目 -
甫司青13475116281 ______ select dname,总薪水,平均薪水,薪水和 from DeptInfo d, (select max(sal) as '总薪水',avg(sal) as '平均薪水',sum(sal) as '薪水和',did from UserInfo group by did) t where d.did = t.did

蓝和晓1839一张名为Test的表中有一个非空的iID字段,将iID设置为主关键字字段,对...
甫司青13475116281 ______ select 成绩 from 课程 natrual join 成绩 where 课程名称like“大学%”and count(选课人数)>5, group by 课程名称

蓝和晓1839SQL语句(题目)
甫司青13475116281 ______ update td set time=getdate() where time is null;修改时间 select * from td where where time is null; 查询表的时间为空的字段