如何将一行项目复制到另一行

Question

我有下表：

Student_ID  Description 
1       0x
2       0x1G800....
3       0x1F800....

Student_ID 1的值为空。如何使用sql查询将Student_ID 2的值复制到1中。

Answer 1

这就是你想要的吗？

Update Student
SET Description = (SELECT Description FROM Student WHERE Student_ID = 2)
WHERE Student_ID = 1

或者使用JOIN:

UPDATE S 
SET S.Description = S2.Description
FROM Student S JOIN
    Student S2 ON S2.Student_ID = 2
WHERE S.Student_Id = 1

祝你好运。