get results by weight factor

[dime_f]

i have problem and i hope somebody will help me to solve it:

 

i have table in mysql with name of something and weight factor (or showing factor)

 

id| names | showing_factor

1| aaaaa  |      5

2| bbbbb  |      4

3| ccccc  |      3

 

my question is: how can i show random names by showing_factor

aaaaa will show most of the time, then bbbbb, then cccc

 

some code of the script but just random show(not random show with factor)

 

 

$sql="select * from table";

$result=mysql_query($sql);

 

while($row=mysql_fetch_row($result)){

$field[]=$row[0];    //i take results from db and put in array

}

 

        $min=min($field);    //  min and max  from array

$max=max($field);

 

$b_id=rand($min,$max);  //get random number of results - BUT NOT WITH SHOWING FACTOR  ???

 

pls help, regards (sorry for my english)