联接上的sql标识符无效

Question

我正在尝试学习JOIN，但我无法让它工作。尝试将第二个表连接到第一个表，以获得除法的名称，即dname变量。

select e.COUNT(empID), e.SUM(salary), e.DID, d.dname
from employee e
right join division on e.DID=d.DID
group by DID

Answer 1

select COUNT(e.empID), SUM(e.salary), e.DID, d.dname
from employee e
right join division d on e.DID=d.DID
group by e.DID, d.dname

Answer 2

您错过了division和Group上的别名d，并且别名进入了选择行上的函数调用中

select COUNT(e.empID), SUM(e.salary), e.DID, d.dname
from employee e
right join division d on e.DID=d.DID
group by e.DID