使用不同的where条件多次计数列

Question

我有一个存储admin_id和comment的表格，我正在尝试查询它以获取与每个管理员相关的不同评论的计数。

我试图这样做：

select admin_id, 
        count(comment like 'Approved the claim for%') as Approved,
        count(comment like 'Rejected the claim for%') as Rejected,
        count(comment like 'Temporarily rejected (24 hour hold) the claim for%') as TempReject, 
        count(comment like 'Permanently rejected the claim for%') as PermReject
from admin_comments
group by admin_id

然而，这会产生结果，其中列Approved，Rejected，TempReject和PermReject都是相同的，以及顶部的一行似乎是在admin_id为NULL的所有位置汇总它们：

我需要在查询中更改哪些内容才能获得按admin_id分组的每种评论类型的准确数据。

Answer 1

试试这个：出于此目的使用CASE表达式

select admin_id, 
    SUM(CASE WHEN comment like 'Approved the claim for%' THEN 1 ELSE 0 END) as Approved,
    SUM(CASE WHEN comment like 'Rejected the claim for%' THEN 1 ELSE 0 END) as Rejected,
    SUM(CASE WHEN comment like 'Temporarily rejected (24 hour hold) the claim for%' THEN 1 ELSE 0 END) as TempReject, 
    SUM(CASE WHEN comment like 'Permanently rejected the claim for%' THEN 1 ELSE 0 END ) as PermReject
from admin_comments
group by admin_id

Answer 2

COUNT不执行布尔表达式，因此您无法在COUNT中使用LIKE。你必须使用CASE / WHEN

select admin_id, 
        count( WHEN comment like 'Approved the claim for%' THEN 1 ELSE NULL END) as Approved,
        count(WHEN comment like 'Rejected the claim for%' THEN 1 ELSE NULL END) ....

请注意，它必须为NULL而不是0，因为COUNT计算非空值。 O是非空值

Answer 3

 select admin_id, 
        count(case when comment like 'Approved the claim for%' then 1 else null end) as Approved,
        count(case when comment like 'Rejected the claim for%' then 1 else null end) as Rejected,
        count(case when comment like 'Temporarily rejected (24 hour hold) the claim for%' then 1 else null end) as TempReject, 
        count(case when comment like 'Permanently rejected the claim for%' then 1 else null end ) as PermReject
    from admin_comments
 group by admin_id