Question

我想阻止这个：

  $florissql = "SELECT SUM(hours) FROM logs WHERE executors LIKE '%floris%'";
  $rosasql = "SELECT SUM(hours) FROM logs WHERE executors LIKE '%rosa%'";
  $lottesql = "SELECT SUM(hours) FROM logs WHERE executors LIKE '%lotte%'";

是否可以只在一个查询中执行此操作？

Answer 1

试试这个吗？

 SELECT SUM(hours) AS Hours, 'floris' AS Executor FROM logs WHERE executors LIKE '%floris%'
 UNION ALL
 SELECT SUM(hours) AS Hours, 'rosa' AS Executor FROM logs WHERE executors LIKE '%rosa%'
 UNION ALL 
 SELECT SUM(hours) AS Hours, 'lotte' AS Executor FROM logs WHERE executors LIKE '%lotte%'

这将导致：

  Hours | Executor
  ----------------
  123   | floris
  456   | rosa
  789   | lotte

Answer 2

此question向您展示如何将GROUP BY与LIKE一起使用...然后您可以执行以下操作：

SELECT
  CASE
    WHEN executors LIKE '%floris%'   THEN 'floris'
    WHEN executors LIKE '%rosa%' THEN 'rosa'
    WHEN executors LIKE '%lotte%' THEN 'lotte'
  END AS exec
, SUM(hours) AS hrs
FROM logs
GROUP BY 
  CASE
    WHEN executors LIKE '%floris%'   THEN 'floris'
    WHEN executors LIKE '%rosa%' THEN 'rosa'
    WHEN executors LIKE '%lotte%' THEN 'lotte'
  END

然后你可以在不同的行上匹配exec的小时数。

我链接的那个问题向您展示了更高级的方法，以防您需要做更多这些......

Answer 3

如果需要每执行者的结果，则以下内容应足够：

SELECT executors, SUM(hours)
FROM logs
WHERE executors LIKE '%floris%'
OR executors LIKE '%rosa%'
OR executors LIKE '%lotte%'
GROUP BY executors

Answer 4

SELECT 
    sum(IF(executors LIKE '%floris%',hours,0)) as 'floris',
    sum(IF(executors LIKE '%rosa%',hours,0)) as 'rosa',
    sum(IF(executors LIKE '%lotte%',hours,0)) as 'lotte'
FROM logs;

但是，您知道，在第一个位置使用%可能会破坏您的数据库性能。因为在那种情况下索引不会使用。尽量避免这种要求。

可以预防多个sql sum查询？

4 个答案: