mysql 1111无效使用组功能

Question

此查询工作正常：

SELECT leads.contact_id, count(leads.contact_id) as orders 
FROM leads
WHERE leads.status="sold" 
GROUP BY leads.contact_id    

但这不是。 为什么？

SELECT leads.contact_id, count(leads.contact_id) as orders
FROM leads
WHERE orders > 1 and leads.status="sold" 
GROUP BY leads.contact_id    

执行此查询时出现错误

1054-“ where子句”中的未知列“ orders”

即使用count（leads.contact_id）替换订单也不起作用：

SELECT leads.contact_id, count(leads.contact_id) as orders
FROM leads
WHERE count(leads.contact_id) > 1 and leads.status="sold" 
GROUP BY leads.contact_id 

返回以下错误消息：

1111-无效使用组功能

Answer 1

如果您了解SQL的操作顺序，您将知道为什么查询不起作用。

FROM clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
ORDER BY clause

在SELECT和GROUP BY之前先评估WHERE子句。 因此，它将不知道count(leads.contact_id)或orders是count(leads.contact_id) 。 HAVING上除后评估GROUP BY 。 它用于过滤聚合。

SELECT leads.contact_id, count(leads.contact_id) as orders 
FROM leads
WHERE leads.status="sold" 
GROUP BY leads.contact_id  
HAVING orders > 1

Answer 2

我应该使用HAVING而不是WHERE，因为WHERE仅可用于过滤原始数据表，而不能用于过滤计算出的数据表。 但是列数（leads.contact_id）或订单是计算列，而不是表的原始列，因此我不得不像这样使用HAVING使其起作用：

SELECT leads.contact_id, count(leads.contact_id) as orders 
FROM leads
WHERE leads.status="sold" 
GROUP BY leads.contact_id  
HAVING orders>1

另请参阅此详细说明