如何通过JOIN从另一个表中查找不存在的数据? [英] How to find non-existing data from another Table by JOIN?
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问题描述
我有两个表TABLE1看起来像:
I have two tables TABLE1 which looks like:
id name address
1 mm 123
2 nn 143
和带有w/c的TABLE2看起来像:
and TABLE2 w/c looks like:
name age
mm 6
oo 9
我想通过将TABLE1
与TABLE2
进行比较来获得不存在的名称.
I want to get the non existing names by comparing the TABLE1
with the TABLE2
.
所以基本上,我必须获得第二行,w/c具有TABLE2
中不存在的NN名称,输出应如下所示:
So basically, I have to get the 2nd row, w/c has a NN name that doesn't exist in the TABLE2
, the output should look like this:
id name address
2 nn 143
我已经尝试过了,但是不起作用:
I've tried this but it doesn't work:
SELECt w.* FROM TABLE1 W INNER JOIN TABLE2 V
ON W.NAME <> V.NAME
并且仍在获取现有记录.
and it's still getting the existing records.
推荐答案
INNER JOIN
在这里无济于事.
解决此问题的一种方法是使用LEFT JOIN
:
One way to solve this is by using a LEFT JOIN
:
SELECT w.*
FROM TABLE1 W
LEFT JOIN TABLE2 V ON W.name = V.name
WHERE ISNULL(V.name);
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