How to concate column values in group rows in mysql

Sometime we face the problems for concatenating of group rows column value in a single string.
Scenario is like this :
We have a table data Like

a b    c 
1 100 name1
1 200 name2
2 150 name1
3 120 name1
3 130 name2
3 100 name3

a b c

1 100 name1

1 200 name2

2 150 name1

3 120 name1

3 130 name2

3 100 name3

now we want result like this :

1 300 name1,name2
2 150 name1
3 350 name1,name2,name3

1 300 name1,name2

2 150 name1

3 350 name1,name2,name3

How we can achieve concatenating of group by rows value.

GROUP_CONCAT() is a function by which we can concate group rows values.
Syntax

 GROUP_CONCAT(expr)

1	GROUP_CONCAT(expr)

For getting above result, we have to write query as follows

select a,sum(b),group_concat(c) from table group by a

1	select a,sum(b),group_concat(c) from table group by a

Please see here for More details