左连接查询的Mysql语法错误

Question

我一直收到此查询的语法错误。我试图找出行的计数，其中：

1）列earnings_campaign_free_id = 43

2）列earnings_campaign_paid_id = 43

所以两个输出：paid_views，free_views

SELECT 

cp.campaign_paid AS paid_views 
cf.campaign_free AS free_views 

FROM 

(
    SELECT COUNT(earning_paid_campaign_id) AS campaign_paid 
    FROM earnings 
    WHERE earning_paid_campaign_id = 43 
) cp 

LEFT JOIN 

(
    SELECT COUNT(earning_free_campaign_id) AS campaign_free 
    FROM earnings 
    WHERE earning_free_campaign_id = 43 
) cf 

ON cf.earning_campaign_free_id = cp.earning_paid_campaign_id 

这是错误：

1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use

near 'cf.campaign_free AS free_views

FROM

( SELECT COUNT(earning_paid_campaign_i' at line 4

怎么办我修复这个错误？

Answer 1

试试这个。

SELECT 

cp.campaign_paid AS paid_views, 
cf.campaign_free AS free_views 

FROM 

(
    SELECT earning_paid_campaign_id,COUNT(earning_paid_campaign_id) AS campaign_paid 
    FROM earnings 
    WHERE earning_paid_campaign_id = 43 
) cp 

LEFT JOIN 

(
    SELECT earning_campaign_free_id,COUNT(earning_free_campaign_id) AS campaign_free 
    FROM earnings 
    WHERE earning_free_campaign_id = 43 
) cf 

ON cf.earning_campaign_free_id = cp.earning_paid_campaign_id 

您试图加入的ON cf.earning_campaign_free_id = cp.earning_paid_campaign_id基础，但是，当你写sub query然后mysql创建temporary表，你没有选择该ID。所以发生错误