从mySQL查询中收集两个单独的列结果

Question

我有两个包含类似数据的数据库表 - 其中一个是进程完成的工作量，另一个是该进程发生的错误数量。

我想显示正确的第一次工作的百分比。

我通过工艺计算的项目数查询：

SELECT Counter.Process, count(Counter.Process) AS count 
          FROM Counter WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
          GROUP BY Counter.Process 
          ORDER BY count DESC 

上面给了我类似的列表：

Process | count 
------------------- 
Process A | 40 
Process B | 32 
Process C | 102 
Process D | 23 

我有第二个表与它相同的字段用于记录错误，称为“错误”。

通过使用相同的查询（但明显改变表名），我可以得到一个进程和错误的列表。

我想要做的是创建一个PHP网页，显示每个进程的错误百分比。

我的问题是，如果我分别创建两个查询，当我使用PHP Where循环遍历它们时，我不知道如何使计算显示百分比。

我试着在两个SQL查询之间使用UNION，但是我无法让它显示出针对该过程的两个不同的计数读数。

理想情况下，我想一个方法来显示这样的数据：

Process | Counter.count | Errors.count 
Process A  40    2 
Process B  32    0 
Process C  102    18 
Process D  23    8 

我真的很感激任何意见/建议，我怎么能做到这一点 - 如果你需要我的数据库的详细信息表，请让我知道

感谢您阅读

小号

Answer 1

你可以使用子查询：

SELECT Counter.Process, count(Counter.Process) AS Count, 
     (SELECT count(Errors.Process) 
     FROM Errors 
     WHERE Process=Counter.Process 
      AND (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59')) AS Errors 
          FROM Counter WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
          GROUP BY Counter.Process 
          ORDER BY count DESC 

Regards， Neil。

Answer 2

我没有运行它，所以可能会有错误。你可以使两个选择，和左连接的结果：

select s.process, s.success_count, e.error_count 
from 
(SELECT Counter.Process as process, count(Counter.Process) AS success_count 
FROM Counter 
WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
GROUP BY Counter.Process 
) s left join 
(SELECT Errors.Process, count(Errors.Process) AS error_count 
     FROM Errors 
     WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
     GROUP BY Errors.Process 
) e 
on (s.Process = e.process) 

Answer 3

我个人更喜欢来用PHP执行这样的情况，因为它混淆了我少，所以我将解释如何，我认为我会做它在PHP（我说“想”，因为我可能不知道一些关于你的数据库结构或系统规范，这将使我的事情，否则）：

$rows = array(); 
$res = mysql_query('SELECT Counter.Process, count(Counter.Process) AS count 
         FROM Counter WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
         GROUP BY Counter.Process 
         ORDER BY count DESC'); 
while ($arr = mysql_fetch_assoc($res)) 
{ 
    $rows[] = $arr; 
} 

$res2 = mysql_query('SELECT Errors.Process, count(Errors.Process) AS count 
         FROM Counter WHERE (TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59') 
         GROUP BY Errors.Process 
         ORDER BY count DESC'); 
while ($arr2 = mysql_fetch_assoc($res2) 
{ 
    for ($i=0; $i<count($rows); $i++) 
    { 
     if ($arr2["Process"] == $data[$i]["process"]) 
     { 
      break; 
     } 
     //Do your functions with $arr and $data[$i] at this point... 
    } 
} 

Answer 4

没有一个子查询做它应该是简单的：

SELECT 
    Counter.Process 
    , COUNT(Counter.Process) AS ProcessCount 
    , COUNT(Errors.Process) AS ProcessErrors 
FROM 
    Counter 
    LEFT JOIN 
    Errors 
    ON Counter.Process = Errors.Process 
WHERE 
    Counter.TIME BETWEEN '2012-07-01 00:00:00' AND '2012-07-06 23:59:59' 
GROUP BY 
    Counter.Process 

您可以对这两个查询进行解释，以查看哪些数据最适合您的数据。

-edit：我已将它更改为LEFT JOIN，因此如果进程没有错误，则不会错过行。