SQL服務器 - 建築更新where子句根據病情

Question

請參考下面的查詢：

Update Employee 
Set AccountManagerId = a.AM_ID 
FROM Employee e INNER JOIN AccountManager a on e.Id = a.Id 
WHERE 

**奮力構建以下部分（它需要被添加到where子句）**

If a.Department is not null then [FOLLOWING NEEDS TO BE ADDED TO WHERE CLAUSE] (e.Department = a.department) 

努力將此添加到where子句。所以，如果部門不爲NULL，然後加入這WHERE子句

Answer 1

Update Employee 
Set AccountManagerId = a.AM_ID 
FROM Employee e INNER JOIN AccountManager a on e.Id = a.Id 
WHERE ((a.Department IS NULL) || (e.Department = a.department)) 

Answer 2

你能不能做：

Update Employee 
Set AccountManagerId = a.AM_ID, 
e.Department = a.department 
FROM Employee e INNER JOIN AccountManager a on e.Id = a.Id 
WHERE 
a.Department IS NOT NULL 

Answer 3

爲什麼不只是添加另一個條件的加入？

我相信這會達到您的目的，只更新具有部門的匹配客戶經理的員工。

UPDATE Employee 
SET AccountManagerId = a.AM_ID 
FROM Employee e 
INNER JOIN AccountManager a 
ON e.Id = a.Id 
AND 
e.Department = a.Department