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31.纠错3 OrderItems表含有order_num订

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31.纠错3

OrderItems表含有order_num订单号

order_num

a002

a004

a007

【问题】将下面代码修改正确后执行

SELECT order_num, COUNT(*) AS items 
FROM OrderItems 
GROUP BY items 
HAVING COUNT(*) >= 3 
ORDER BY items, order_num;

【示例结果】

返回订单号order_num和出现的次数items

order_num	items
a002	3

【示例解析】

由于订单号a002出现了三次，所以返回3

SELECT order_num, COUNT(*) AS items
FROM OrderItems
GROUP BY order_num
limit 1

SELECT order_num, COUNT(order_num) AS items
FROM OrderItems
where order_num='a002'
GROUP BY order_num

SELECT order_num, COUNT(*) AS items
FROM OrderItems
GROUP BY order_num
HAVING items >= 3
ORDER BY order_num

SELECT order_num, COUNT(*) AS items
FROM OrderItems
GROUP BY order_num
ORDER BY order_num;

查看正确选项

牛客424223581号

having在select之前执行，items列还没创立怎么就having items了？

编辑于 2025-03-22 20:13:19 回复(0)

灿灿灿灿灿_

A应该是对的啊我在mysql中运行了相同的代码结果是可以出来的啊

发表于 2024-10-06 11:29:53 回复(0)

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问题信息

来自：SQL必知必会（下）

上传者：小小

难度：

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