根据COUNT行数过滤分组结果

Question

我基本上有一个非常简单的查询，像这样

SELECT accounts . * , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
GROUP BY followings.receive
ORDER BY COUNT(receive) DESC

我尝试将其更改为以下内容，但失败了

SELECT accounts . * , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
    AND total_accounts < 10
GROUP BY followings.receive
ORDER BY COUNT(receive) DESC

Unknown column 'total_counts' in 'where clause'

很抱歉发布这样一个简单的问题，但我的想法现在陷入僵局

Answer 1

首先： 删除表格和* ： accounts.* 之间的空间 。

第二：您不能在聚合表达式上使用where 。 您需要使用having ：

SELECT accounts.* , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
GROUP BY followings.receive
HAVING total_accounts < 10
ORDER BY COUNT(receive) DESC

有关select如何工作的一些指南：

SELECT "Fields and expressions"
FROM "Tables, views and / or subqueries"
WHERE "Conditions to apply on the raw data (contained directly in the FROM clause)"
GROUP BY "Grouping fields"
HAVING "Conditions to apply on the grouped data or (aggregate) expressions"

Answer 2

要在 GROUP BY子句之前过滤，请使用WHERE ， 然后在过滤之前 ，使用HAVING 。 由于count的汇总是在分组期间发生的，因此它在WHERE子句中给出了错误-在执行时根本不知道。 改成：

SELECT accounts.* , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
GROUP BY followings.receive
HAVING count(receive) < 10
ORDER BY COUNT(receive) DESC

Answer 3

SELECT accounts.* , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
GROUP BY followings.receive  --<-- You need to GROUP BY All the columns
                                 -- In your select that are not containted 
                               -- in any Aggregate Function i.e accounts.*


ORDER BY total_counts DESC  --<-- ORDER BY you need to use the Alias

查询2

SELECT accounts.* , COUNT(receive) as total_counts
FROM followings
LEFT JOIN accounts ON followings.receive = accounts.account_id
WHERE accounts.status <1
  --  AND total_accounts < 10 --<-- Where Clause Filters the Rows
                                -- Before doing any aggregates you
                                -- need to use HAVING Clause when checking
                                -- against aggregated values

GROUP BY followings.receive   --<-- You need to GROUP BY All the columns
                                 -- In your select that are not containted 
                               -- in any Aggregate Function i.e accounts.*
HAVING total_accounts < 10
ORDER BY total_counts DESC --<-- ORDER BY you need to use the Alias