Question

我将使用示例表。

tblAnimal：

---------------------------------
|Animal    | Colour |  Gender   |
---------------------------------
|Dog       |        |           |
---------------------------------

tblDescription：

-------------------------------
| Animal |  ID  | Description |
-------------------------------
|  Dog   |   1  |    Male     |
-------------------------------
|  Dog   |  92  |   White     |
-------------------------------

所以我想更新tblAnimal，以便填充颜色和性别。

我使用了代码

UPDATE tblAnimal
SET Colour = CASE WHEN tblDescription.ID = 92 THEN tblDescription.Description END,
    Gender = CASE WHEN tblDescription.ID = 1 THEN tblDescription.Description END
FROM tblDescription INNER JOIN tblAnimal 
    ON tblDescription.Animal = tblAnimal.Animal

但它不起作用。 tblAnimal中的两列都保持为NULL。看起来SQL Server只检查tblDescription中的第一行。

我如何编写此UPDATE语句，以便颜色和性别都是tblDescription中的内容？

修改

谢谢大家的解决方案！是的，表需要进行规范化，但这仅仅是为了在UPDATE语句中提出我的问题。

再次感谢大家。

Answer 1

试试这个：

UPDATE tblAnimal a
SET
    a.Colour = (SELECT d.Description d FROM tblDescription d WHERE d.Animal = a.Animal AND ID = 92),
    a.Gender = (SELECT d.Description d FROM tblDescription d WHERE d.Animal = a.Animal AND ID = 1)

Answer 2

Create table tblDescription(
Animal varchar(20),
ID int,
Description varchar(20)
)

Insert into tblAnimal(Animal)
values ('Dog')

Insert into tblDescription
Select 'Dog',1,'Male' union all
Select 'Dog',92,'White'

Select * from tblAnimal

Select * from tblDescription

---Update

Update a
SET Colour = (Select d.description from tbldescription d where d.id =92),
Gender = (Select d.description from tbldescription d where d.id =1)

From tblAnimal a inner join
tblDescription d on d.Animal =a.Animal

注意：这样可行，但我要做的是对tbldescription进行规范化。

Answer 3

另一种方式：

UPDATE tblAnimal
    SET colour = (select  Description from  tblDescription where ID = 92),
        Gender = (select  Description from  tblDescription where ID = 1)

Answer 4

您需要在tblAnimal中拥有ID引用才能获得与tblDescription的关联。

tblAnimal：

---------------------------------
|Animal | ID   | Colour |  Gender|
---------------------------------
|Dog    |  1  |         |       |
---------------------------------
|Dog    |  92 |         |       |
---------------------------------

然后你可以运行：

UPDATE 
  tblAnimal as a
SET
  Colour = (SELECT Description from tblDescription x WHERE x.id = a.id),
  Gender = (SELECT Description FROM tblDescription x WHERE x.id = a.id)

带有CASE语句的SQL Update

4 个答案: