Question

我有下表：

id   | user | createdAt           | pstatus  
-------------------------------------------------------
287  | Foo  | 2013-08-01 17:19:24 | PLAYING  
286  | Foo  | 2013-08-01 17:18:24 | IDLE  
285  | Foo  | 2013-08-01 17:17:24 | PLAYING  
284  | Foo  | 2013-08-01 17:16:24 | BUFFERING 
283  | Foo  | 2013-08-01 17:15:24 | STOPPED

如何查询此表以产生以下结果？基本上，我需要获得每个用户每天不同pstatus值的总数。

User | logdate    | playCount | idleCount | bufferCount | StopCount
-------------------------------------------------------------------
Foo  | 2013-08-01 |         48|        62 |           0 |         4
Foo  | 2013-08-02 |         25|        22 |           0 |         0
Bar  | 2013-08-02 |         22|        32 |           5 |         4
Bar  | 2013-08-03 |         44|        11 |           1 |         0
Foo  | 2013-08-03 |         32|        03 |           0 |         0

我知道我可以使用DATE（createdAt）来获取每天的日期而不是时间戳，但我正在努力将以下内容合并到一个查询中：

COUNT(pstatus) AS playCount WHERE pstatus = "PLAYING";
COUNT(pstatus) AS idleCount WHERE pstatus = "IDLE";
COUNT(pstatus) AS bufferCount WHERE pstatus = "BUFFERING";
COUNT(pstatus) AS StopCount WHERE pstatus = "STOPPED";

我很确定它需要是子查询，但在语法上挣扎！

Answer 1

您可以使用SUM条件，这将导致布尔值，并根据条件为您提供计数

SELECT
DATE(createdAt) logdate,    
SUM(pstatus = "PLAYING") playCount 
,SUM(pstatus = "IDLE") idleCount 
,SUM(pstatus = "BUFFERING") bufferCount 
,SUM(pstatus = "STOPPED") StopCount
FROM `table`
GROUP BY `User`,DATE(`createdAt`)

Demo

Answer 2

试试这个：

   SELECT 
  SUM(CASE 
         WHEN pstatus = "PLAYING" THEN 1
         ELSE 0
       END) AS sumPLAYING,
   SUM(CASE 
         WHEN pstatus = "IDLE" THEN 1
         ELSE 0
       END) AS sumIDLE,

   SUM(CASE 
         WHEN pstatus = "BUFFERING" THEN 1
         ELSE 0
       END) AS sumBUFFERING,
   SUM(CASE 
         WHEN pstatus = "STOPPED" THEN 1
         ELSE 0
       END) AS sumSTOPPED
FROM YOUR_TABLE

带COUNT的子查询（mysql）

2 个答案: