从同一个表

Question

我有一个包含以下属性的员工数据表

Id Emp_name Supervisor_Name Supervisor_id
1   A           B
2   B           
3   C           B

我想更新Supervisor_Id列，Id值等于Supervisor_Name。输出如下。

Id Emp_name Supervisor_Name Supervisor_id
1   A           B               2
2   B           
3   C           B               2

执行此操作的最佳SQL查询是什么

Answer 1

INNER JOIN使用UPDATE t1 SET t1.Supervisor_id = t2.Id FROM mytable t1 INNER JOIN mytable t2 ON t1.Supervisor_Name = t2.Emp_name 语法：

{{1}}

http://www.hackviking.com/development/python-get-user-info-after-oauth/

Answer 2

自我加入可以胜任

update e1
set e1.Supervisor_id=e.id
from Employee e1
join Employee e
on e1.Supervisor_Name =e.Emp_name