mysql - AND 运算符在 SQL 中给出错误的输出

Question

我正在触发这个查询

SELECT *
FROM Orders WHERE (CustomerID <> 51) AND (ShipperID <> 3);

并且它没有显示具有不同 shipperid 的 CUSTOMERS WITH 51

为什么？是他们在 sql 中对 AND 的任何不同看法

如果我想排除 customerid 为 51 和 shipper id 为 3 的记录，但显示 customerid 为 51 和 shipper 不包括 3 的记录怎么办？

Answer 1

正如您所述它没有显示 CUSTOMERS WITH 51 with different shipperid我想你更想说

SELECT * FROM Orders WHERE CustomerID = 51

so what if i want to exclude records with customerid with 51 and shipper id with 3 but show customerid with 51 and shipper excluding 3?

然后把你的条件改成

SELECT * FROM Orders 
WHERE (CustomerID <> 51 AND ShipperID <> 3)
OR (CustomerID = 51 AND ShipperID <> 3);