Mysql添加并将它们添加为新列

Question

我想获取2个coulmns数并将它们的总数作为新列。 我该怎么做？

我写了这个查询，但是这总是返回错误。

SELECT count(case when `status`='1' then 1 else 0 end) AS HOT, 
count(case when `status`='5' then 1 end) 
AS Special_Case,count(case when 1=1 then 1 end) AS TOTAL 
FROM `tbl_customer_conversation` group by 
date(`dt_added`),user_id 

Answer 1

COUNT只会给一个记录是匹配的时候，就是在你的查询将始终返回1，因为该值可以是1或0。所以count(1)也是1和count(0)也是1。

AS，你想要的总数为HOT个案和SPECIAL_CASE你必须使用SUM。

SELECT 
    SUM(case when `status`='1' then 1 else 0 end) AS HOT, 
    SUM(case when `status`='5' then 1 end) AS Special_Case, 
    SUM(case when `status` = '1' or `status` = '5' then 1 end) AS TOTAL 
FROM `tbl_customer_conversation` 
group by date(`dt_added`),user_id