MySQL Pivot Query with Sum of column value

Question

Table 1(reports) - Structure with Data

id  distributorId clientId amount
1       1            162    2500
2       2            163    3500
3       3            203    4500
4       6            157    5500
5       1            162    1500
6       3            163    2000
7       3            162    1000

Table 2(distributor) - Structure with Data

id    distributor
1        Dis A
2        Dis B
3        Dis C
6        Dis D

Table 3(clients) - Structure with Data

id    client_name
162     Client A
163     Client B
203     Client C
157     Client D

Desired Output Using the above defined 3 tables:

client_name    Dis A    Dis B    Dis C    Dis D
 Client A      4000      0       1000      0
 Client B       0        3500    2000      0
 Client C       0        0       4500      0
 Client D       0        0        0       5500

Answer 1

For the fixed pivot sql, try this:

select
    t.client_name,
    sum(if(t.distributor = 'Dis A', t.amount, 0)) as `Dis A`,
    sum(if(t.distributor = 'Dis B', t.amount, 0)) as `Dis B`,
    sum(if(t.distributor = 'Dis C', t.amount, 0)) as `Dis C`,
    sum(if(t.distributor = 'Dis D', t.amount, 0)) as `Dis D`
from (
    select c.id, c.client_name, d.distributor, r.amount
    from clients c
    left join reports r on c.id = r.clientId
    left join distributor d on d.id = r.distributorId
)t
group by t.id
order by t.client_name

SQLFiddle DEMO HERE

For the dynamic pivot sql, try this:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'sum(if(t.distributor = ''',
      distributor,
      ''', t.amount, 0)) AS `',
      distributor ,'`'
    )
  ) INTO @sql
FROM distributor;
SET @sql = CONCAT('SELECT t.client_name, ', @sql, ' FROM (
    select c.id, c.client_name, d.distributor, r.amount
    from clients c
    left join reports r on c.id = r.clientId
    left join distributor d on d.id = r.distributorId
)t
group by t.id
order by t.client_name');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SQLFiddle DEMO HERE

Answer 2

Try this one.

with new_table as
(
select 
    T3.client_name as client,
    sum(case when T1.distributorId = '1 ' then amount end) as  'Dis A',
    sum(case when T1.distributorId = '2 ' then amount end) as  'Dis B',
    sum(case when T1.distributorId = '3 ' then amount end) as  'Dis C',
    sum(case when T1.distributorId = '6 ' then amount end) as  'Dis D'
FROM reports T1
JOIN distributor T2 on T2.id = T1.distributorId
JOIN clients T3 on T3.id = T1.clientId 
)

select 
    client,
    Dis A ,
    Dis B,
    Dis C,
    Dis D
FROM New_Table
group by 1