无法绑定多部分标识符的原因

error - The multi-part identifier "Grant.EmpID" could not be bound.

错误-多部分标识符“授予”。“不能被束缚”。

query -

查询-

select emp.EmpID, 
COUNT(*) as CountRecords,
COUNT(GrantName) AS CountValues
From Employee as emp full join [Grant] as gr
on emp.EmpID = [Grant].EmpID 
-- This is the cause for the error ! Change it to gr.EmpID
group by emp.EmpID

Why does this error occur ? Can't I call a person by real name and also by nickname ?

为什么会发生这种错误?我不能用真名和绰号叫人吗?

2 个解决方案

#1

You're aliasing [Grant]. In other words, you're stating that from here on out, [Grant] will be referred to as gr.

你混叠(拨款)。换句话说，您正在声明，从现在开始，[Grant]将被称为gr。

Use the ALIAS in the GROUP BY clause, not the tableName.

使用GROUP BY子句中的别名，而不是tableName。

SELECT emp.EmpID, 
       COUNT(*) as CountRecords,
       COUNT(GrantName) AS CountValues
FROM   Employee as emp 
       FULL JOIN [Grant] as gr
          on emp.EmpID = gr.EmpID  -- use the alias.
GROUP BY gr.EmpID                  -- use the alias.

here's the SQL Order of Operation

这是操作的SQL命令。

FROM clause
从条款
WHERE clause
WHERE子句
GROUP BY clause
GROUP BY子句
HAVING clause
有条款
SELECT clause
SELECT子句
ORDER BY clause
ORDER BY子句

#2

No you can't because sql server is not a human. imagine we have an Employee table which references itself

不行，因为sql server不是人。假设我们有一个引用自己的Employee表

select * 
from Employee Emp, Employee Mng
where Emp.ManagerID = Mng.EmployeeID

Mng and Emp are two instances of Employee

Mng和Emp是Employee的两个实例。

so if I select

如果我选择

select * from Employee e, Employee

it will return all employee TWO times, because I am telling give me employees once under the name Employee once under the name e (alias)

它将会返回所有员工2次，因为我告诉给我员工曾经在名字下面的雇员名字e(别名)

#1