Don't.
Instead, have a separate table which uses a foreign key back to the original, and contains the value you want to select:
SalesStaff
ID Name
1 Joe
2 Mike
Sales
Id SalesId Value
1 1 100
2 1 200
3 2 300
And then use and SQL Join to "tie them together"
SELECT ss.ID, ss.Name, s.Value FROM Sales s
JOIN SalesStaff ss
ON ss.ID = s.SalesID
That gives you:
1 Joe 100
1 Joe 200
2 Mike 300
While it is possible to store multiple values in a single column but converting them to strings and comma separating them, it's a PITA to work with and always gives problems. For example, what happens if you want to delete the "500" from "1,2,330,500,5000,200,5"? It's a real pain!