I want to write a user-defined Aggregate Function

[Adnan Raza]

I want to write a custom aggregate function in mySQL just like min or max. What I want to do is to take an array as an argument in a function which will process it and return a single value.

For instance, If we have a table with data as below.
tbl
ID | NAME | Serial
1 | A | A90
2 | A | A91
3 | A | A92
4 | A | A97
5 | A | A98
6 | A | A99

and we want to use a query that groups it by using "group by"
select min(Serial) as starting_nbr, min(Serial) as ending_nbr
from tbl
group by NAME;

the result would be
starting_nbr | ending_nbr
A90 | A99


but I want following output, which is probably not possible by using min and max functions.

Output
A90-A92, A97-A99

To achieve above output, I need to write an aggregate function or any other solution, if possible.