求一条报表sql

Question

detailTable表
id   categoryid     severityId  name
1    1              1           name1
2    1              2           name2
3    1              3           name3
4    2              1           name4
5    2              2           name5
6    2              2           name6categoryTable表
categoryid      descripiton
 1              category1
 2              category2
 3              category3severityTable表
severityId      descripiton
1               NORMAL
2               WARNING
3               MAJOR最后要求的查询结果如下：
categoryDesc  NORMAL  WARNING  MAJOR  total
category1     1       1        1      3
category2     1       2        0      3
category3     0       0        0      0请赐sql

Answer 1

select d.descripiton,
sum(decode(severityId,1,1,0)) normal,
sum(decode(severityId,2,1,0)) warning, 
sum(decode(severityId,3,1,0)) major,
count(*) 
from(select a.descripiton,c.severityId from categoryTable a,detailTable c
where a.categoryid = c.categoryid) d group by description大致就这个思路

Answer 2

你这样category3为空的，好象没显示吧。
categoryDesc  NORMAL  WARNING  MAJOR  total
category3     0       0        0      0，

Answer 3

select c.descripiton categoryDesc,c.NORMAL NORMAL,c.WARNING  WARNING,c.MAJOR  MAJOR,sum(*) total from detailTable a,categoryTable b,severityTable c where a.categoryid =b.categoryid and c.severityId=a.severityId
个人见解  请自己测试。。

Answer 4

再提一个要求 
          categoryDesc    NORMAL    WARNING    MAJOR    total            category1       1         1          1            3  
          category2       1         2          0            3   
          category1       0         0          0            0   sum                       2         3          1            6
就是显示 最后一行，总共的sql