将多行的选定列合并为一行

Question

I want to count the number of male & female user of each religion of each age to obtain a resulting table like the third table below.

tbl_user:

id  name      dob           gender religion
1   raj       1999-12-21       m      1 
7   raju      1998-10-10       m      2 
8   rajan     2000-11-23       m      3 
11  neetu     1992-12-06       f      1 
12  sita      1993-06-16       f      2 
13  rita      1992-06-08       f      3 
14  jenny     1993-05-10       f      2 
15  manju     1993-12-16       f      1 
16  aanju     1993-03-05       f      3 
17  raja      1995-04-06       m      1 
18  rajendra  1995-07-03       m      2 
19  rajesh    1991-05-02       m      3

tbl_religion:

id  name 
1   Christian 
2   Hindu 
3   Islam

Now I want to count the number of male & female user of each religion of each age to obtain a resulting table like the one below. The user can be of any age or or born on any year:

Age Christian Male Christian Female Hindu Male Hindu Female Islam Male Islam Female 
14        0             0           0         0             1            0 
15        1             0           0         0             0            0 
16        0             0           1         0             0            0 
20        1             0           1         0             0            0 
21        0             1           0         0             0            0 
22        0             1           0         2             0            1 
23        0             0           0         0             1            1 
24        0             0           0         0             0            0 

Answer 1

You can use the timestampdiff function to calculate the age, and use conditional aggregation to count the number in each category like below.

select 
    timestampdiff(year, dob, now()) age 
    , sum(gender = 'm' and r.name = 'Christian') Christian_Male
    , sum(gender = 'f' and r.name = 'Christian') Christian_Female
    , sum(gender = 'm' and r.name = 'Hindu') Hindu_Male
    , sum(gender = 'f' and r.name = 'Hindu') Hindu_Female
    , sum(gender = 'm' and r.name = 'Islam') Islam_Male
    , sum(gender = 'f' and r.name = 'Islam') Islam_Female
from tbl_user u
join tbl_religion r on u.religion = r.id 
group by timestampdiff(year, dob, now());

Sample SQL Fiddle