MySQL内部连接不等于运算符

Question

我在Sale中有很多行，并且SalesProcessed中有一行。

SELECT * FROM Sale 
    INNER JOIN SalesProcessed 
    ON Sale.id<>SalesProcessed.id 
    LIMIT 0,30 

此代码返回SalesProcessed中id相同的行。为什么？

其实我需要销售行中哪些ID在SalesProcessed中不存在。

Answer 1

SELECT * 
    FROM Sale 
     LEFT JOIN SalesProcessed 
      ON Sale.id = SalesProcessed.id 
    WHERE SalesProcessed.id IS NULL 
    LIMIT 0,30 

Answer 2

另一种方法

SELECT * FROM Sale 
where Sale.id not in (select SalesProcessed.id from SalesProcessed) 
LIMIT 0,30 



SELECT * FROM Sale 
where NOT EXISTS (
select SalesProcessed.id from SalesProcessed where Sale.id=SalesProcessed.id) 
LIMIT 0,30 

您应该检查与得到最好的结果

Answer 3

如果你想不存在行解释每个查询，这是错误的查询：

SELECT * 
FROM Sale 
LEFT JOIN SalesProcessed 
ON Sale.ID = SalesProcessed.id 
WHERE SalesProcessed.id IS NULL;