Help String To Array

Hello friends
Please help me convert text to array
User[playerid][carid] => "401,402,403,407,500,520" => That will be read from a MySQL field
I want in an array
To be
ListCar[TOTAL_ITEMS] = {401,402,403,407,500,520};
How to Convert User[playerid][carid] > ListCar[]
Please Help Me
Tanks