多连接查询中的SQL总和

Question

我正在为此做准备。 这是第一个表的设置。 第一个查询仅适用于特定日期（例如2012-06-01）之后的项目。

|                  Table: TIMELOG                  |
| INQUIRY_ID | … |      LOGMINS    | … |  OPERID   | … |    EDATE    |
|     2      |   |       45        |   |  bob      |   | 2012-05-01  |
|     5      |   |       3         |   |  richard  |   | 2012-06-02  |
|     5      |   |       12        |   |  bob      |   | 2012-07-01  |
|     5      |   |       15        |   |  paul     |   | 2012-07-01  |
|     6      |   |       10        |   |  paul     |   | 2012-07-01  |

然后，查询需要使用INQUIRY_ID进入不同的表并获得一些其他字段（在此下一个表中，每个INQUIRY_ID只有一个条目：

|                  Table: INQUIRY                  |
| INQUIRY_ID | … |  CATEGORY_ID    | … |  PROD_ID  |
|     2      |   |       45        |   |  6        |
|     3      |   |       3         |   |  50       |
|     4      |   |       12        |   |  3        |
|     5      |   |       15        |   |  67       |
|     6      |   |       10        |   |  2        |

一旦有了CATEGORY_ID和PROD_ID，这些名称的“好记的名称”就在各自独立的表中

|            Table: CATEGORY            |
| CATEGORY_ID | … |      CATNAME        |
|     45      |   |       Server        |
|     3       |   |       Workstation   |
|     12      |   |       Phones        |
|     15      |   |       Backup        |  
|     10      |   |       Network       |

|            Table: PROD                |
| PROD_ID     | … |      PRODDESC       |
|     6       |   |       SBS 2003      |
|     50      |   |       Windows 7     |
|     3       |   |       iPhone        |
|     67      |   |       Buexec        |  
|     2       |   |       SwitchF       |   

然后，我想总计LOGMINS字段，请记住，有时每个INQUIRY_ID会有多个LOGMINS

| INQUIRY_ID | … |      TOTAL      | … |  CATNAME         | … |   PRODDESC    |
|     2      |   |       45        |   |     Server       |   |   SBS 2003    |
|     5      |   |       30        |   |     Workstation  |   |   Windows 7   |
|     6      |   |       10        |   |     Phones       |   |   iPhone      |

对于这么多的细节，我感到抱歉，我尝试过的查询只是炸开了，当我进入嵌套查询和多个联接时，我在SQL方面的技能崩溃了。 任何帮助将不胜感激。

查询我现在正在运行：

 select 
 timelog.INQUIRY_ID,
 SUM (logmins) AS Total,
 catname,
 proddesc,
 EDATE
from
 timelog
inner join inquiry on timelog.inquiry_id=inquiry.inquiry_id
inner join category on inquiry.category_id = category.category_id
inner join prod on inquiry.prod_id = prod.prod_id
where EDATE > '2013-07-01'
group by
timelog.INQUIRY_ID,
catname,
proddesc,
edate
order by timelog.INQUIRY_ID desc

Answer 1

将数据所在的表连接在一起，然后对保持不变的数据进行group ，然后对要添加的字段sum

select 
  inquiry.inquiry_id,
  SUM(logmins),
  catname,
  proddesc
from
   timelog
    inner join inquiry on timelog.inquiry_id=inquiry.inquiry_id
    inner join category on inquiry.category_id = category.category_id
    inner join prod on inquiry.prod_id = prod.prod_id
group by
  inquiry.inquiry_id,
  catname,
  proddesc