# select Name as Customers from Customers
# where Customers.Id not in (select CustomerId from Orders )
将两张表左连接,显示CustomerId为空的名字
# select Name as Customers from Customers
# left join Orders on Customers.Id = Orders.CustomerId
# where CustomerId is NULL
将两张表右连接,和上面左连接思路相反
# select Name as Customers from Customers c where c.Id not in (select Customers.Id from Customers right join Orders on Customers.Id = Orders.CustomerId)
查询没有买单顾客的名字
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转载自blog.csdn.net/weixin_43332500/article/details/88386104
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