Question

我有2个表，Table1 (Id, Name, Email)和Table2 (Id, ItemName, Price, IsShipping)。我需要在Id列上加入它们，但IsShipping列的值为NULL，我需要将NULL更改为0。

现在我有：

SELECT Table1.Id, Table1.Name, Table1.Email, Table2.ItemName, Table2.Price, Table2.IsShipping 
FROM Table1
JOIN Table2
ON Table1.Id = Table2.Id
--here I need to make something like:
WHERE IsShipping IS NULL = 0 -- or etc

Answer 1

使用ANSI标准函数coalesce()：

SELECT t1.Id, t1.Name, t1.Email, t2.ItemName, t2.Price,
       coalesce(t2.IsShipping , 0) as IsShipping
FROM Table1 t1 JOIN
     Table2 t2
     ON t1.Id = t2.Id;

我还添加了表别名。它们使查询更容易编写和阅读。

Answer 2

您可以使用coalesce()，ISNULL和COALESCE都是ANSI标准

SELECT Table1.Id, Table1.Name, Table1.Email, Table2.ItemName, Table2.Price, 
coalesce(Table2.IsShipping,0) as IsShipping
FROM Table1
JOIN Table2
ON Table1.Id = Table2.Id

Answer 3

您可以在以下内容中使用ISNULL：

ISNULL用指定的替换值替换NULL。

SELECT t1.Id, t1.Name, t1.Email, 
       t2.ItemName, t2.Price, 
       ISNULL(t2.IsShipping, 0)  -- Here you pass ISNULL
FROM Table1 t1
JOIN Table2 t2
ON t1.Id = t2.Id

如何从2个表中选择数据并将NULL转换为0？

3 个答案: