SQL query Help

i want to make a query state below .
table salesman table
sid , sname ,sqty ,
1      karim   3     
2      rohim  4
3     kader    8

customer table 
cid , cname , sid
1     robin    1
2     kobir     1
3   jabir      2
4   jisan      2

if i click on first row it will generate 2 row as it have two cust id 1 ,
the entry table will be like this
distribution table
like
this 
cid  , cqty
1      null
2     null

user will insert data in this table if i insert  3 more then th ...