oracle中如何命名查询出来的新列?

来源：百度知道 编辑：UC知道 时间：2024/07/02 04:18:10
我在oracle中在学生表里查询学生的平均成绩以及所学课程的数目, select sno, avg(grade),count(*) from enrolls group by sno;
一切正常,但是如果改成
select sno, avg(grade),'courses'=count(*) from enrolls group by sno;
或者去掉courses上的引号也不行
就会出现"ORA-00923: 未找到要求的 FROM 关键字"
的提示错误,请教高手,oracle中能如此命名吗?

select sno, avg(grade),count(*) courses from enrolls group by sno;

在查询的count(*)后边直接写东西就是重新命名那个字段了
当然count(*) as courses 加上as也可

select sno, avg(grade),count(*) courses from enrolls group by sno;
或者
select sno, avg(grade),count(*) AS courses from enrolls group by sno;

select sno A, avg(grade) B,count(*) c from enrolls group by sno;

不能有‘=’号
select sno, avg(grade),count(*) as courses
from enrolls group by sno;
或
select sno, avg(grade),count(*) courses
from enrolls group by sno;