mysql - WHERE value IS NOT IN(子查询)

Question

我一直在努力解决这个问题。 我有两张 table 。一张带有优惠券和发票编号。一个带有发票编号和客户名称。

我需要获取尚未使用给定优惠券的客户。

表格如下:

促销表:

Promotions
Invoice | Coupon
----------------
1       | couponA
2       | couponB
3       | couponB

订单表:

Orders
Invoice | Customer
------------------
1       | Jack
2       | Jack
3       | Jill

所以 Jack 使用了优惠券 A 和 B，而 Jill 只使用了优惠券 B。

如果我的查询是选择未使用优惠券 A 的客户，我应该找 Jill。

这行得通，但看起来笨拙且缓慢。有没有更好的办法？

SELECT Customer 
FROM Promotions INNER JOIN Orders
ON Promotions.Invoice = Orders.Invoice
WHERE Customer NOT IN(
    SELECT Customer 
    FROM Promotions INNER JOIN Orders
    ON Promotions.Invoice = Orders.Invoice
    WHERE Coupon = couponA)
GROUP BY Customer

感谢您的关注!

编辑: 这是一个 SQLFiddle 模式 http://sqlfiddle.com/#!2/21d31/6

Answer 1

更新:我们应该更喜欢使用连接以获得更好的性能，因为它对我们来说很容易做到。 Join vs. sub-query

Sql Fiddle

Select distinct Customer from orders o
join 
(
  SELECT distinct Customer as changedname FROM Orders o2 
  join
  (
     Select distinct invoice from Promotions where Coupon='couponA'
  ) t3
  on o2.invoice = t3.invoice      
) t2
on o.customer != t2.changedname;

注意:我为 t3 更改了列名 customer，因为两个连接表必须具有不同的列名

解释:

当您拥有大数据时，使用内部查询或子查询的成本很高。改为使用连接，让我们学习将子查询转换为连接

使用子查询我们有:

Select distinct Customer from orders where customer not in 
(SELECT distinct Customer FROM Orders where invoice in
(Select distinct invoice from Promotions where Coupon='couponA'));

转换子查询加入

第一步:

Select distinct Customer from orders o
join 
(
  SELECT distinct Customer as changedname FROM Orders where invoice in
  (Select distinct invoice from Promotions where Coupon='couponA')
) t2
on o.customer != t2.changedname;

第二步:

Select distinct Customer from orders o
join 
(
  SELECT distinct Customer as changedname FROM Orders o2 where invoice 
  join
  (
     Select distinct invoice from Promotions where Coupon='couponA'
  ) t3
  on o2.invoice = t3.invoice      
) t2
on o.customer != t2.changedname;

就是这样，对于有很多行的表来说要快得多

原答案:

使用不在。看看。

Select distinct Customer from orders where customer not in 
(SELECT distinct Customer FROM Orders where invoice in
(Select distinct invoice from Promotions where Coupon='couponA'));

编辑 我添加了 distinct 以加快查询速度

SQL Fiddle