MySQL：选择COUNT记录

Question

我正在尝试选择已准确订购1个订单的1000个客户。一切都在Orders表中。

  

从Order中选择*计数（CustomerID）= 1限制1000

基本上所有记录在整个表中只有一个CustomerID出现。这将返回一个空结果集，表中有100,000个。

Answer 1

您需要GROUP才能（有意义地）使用HAVING子句。以下按预期工作：

SELECT
    *
FROM
    `Order`
GROUP BY
    CustomerID
HAVING
    COUNT(CustomerID) = 1
LIMIT 1000

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<强>更新
添加WHERE（参见评论）：

SELECT
    *
FROM
    `Order`
WHERE
    Language = 'EN'
GROUP BY
    CustomerID
HAVING
    COUNT(CustomerID) = 1
LIMIT 1000

Answer 2

SELECT * FROM `Order`
GROUP BY CustomerID 
HAVING COUNT(CustomerID) = 1 
LIMIT 1000

Answer 3

试

select count(CustomerID) as counter ,o.* from Order o
group by CustomerID having  counter  = 1  limit 1000

Answer 4

添加group by以查询正确的输出，例如：

选择* 来自订单 按客户ID分组 有计数（CustomerID）= 1 限制1000

Answer 5

SELECT CustomerID FROM Order GROUP BY CustomerID HAVING COUNT（*）= 1 LIMIT 1000