Combine cells with same worker names and sum all his hours with PHP/MySQL

Question

I don't know how to combine and sum rows with same values from MySQL database with PHP language. I have database that has ID, Machine, Worker1, Worker2, Worker3, Hours1, Hours2, Hours3. For example if Worker1 is John than his hours are Hours1; if Worker2 is John than his hours are Hours2. Database contains a lot of workers and a lot of machines and this is just simple example:

table name = entry 

ID    Machine    Worker1   Worker2   Worker3   Hours1   Hours2   Hours3
1       M1        John      Adam                  5       7
2       M2        Adam      Bruce                10       1
3       M1        Mark      John                  3       2
4       M1        John      Marry      Adam       8       9        6
...

What I need is report like this to be selected from MySQL with PHP language to combine worker cells with same name in one cell and sum all his hours in one cell for the selected Machine:

Machine = M1
-----------------------------
Worker     Hours
 John        15
 Adam        13
 Mark         3
 Marry        9
------------------------
Total;       40

I appreciate for your help and time.

Answer 1

You need to use the group by in your sql.

SELCT SUM(Hours1),Worker1 FROM table_name WHERE Machine='M1' GROUP BY Worker1

You might also want to check http://www.w3schools.com/sql/sql_groupby.asp

Answer 2

select worker, sum(Hour) as Hours from

(select sum(Hours1) as Hour,Worker1 as Worker from entry where Machine='M1' group by Worker1

UNION

select sum(Hours2) as Hour,Worker2 as Worker from entry where Machine='M1' group by Worker2 UNION

select sum(Hours3) as Hour ,Worker3 as Worker from entry where Machine='M1' group by Worker3) t1

where worker IS NOT NULL group by Worker ORDER BY Hours DESC

SqlFiddle Link