i am reading data form excsl sheet in which first column is mobile numbers.

and then in a loop storing them one by one in databse table.

now i want to have a check that reapeated mobile numbers should not be entered in table.wht should i do to have this check? is thier sny function for this?
i was thinking to store mobile numbers in an aray and checking them. but i think it will take a bit of time.but if no other solution then how can i check in this manner also???