sql - query for a scenario using other then Case statement -

i have table t1, columns custid, customername, q1, q2, q3, q4, deptid. , custid values 1,2,3...so on.

but q1, q2, q3, q4 values either 'y' or 'n' or null.

total table t1 is:

custid  custname  q1    q2    q3   q4   deptid 1       john        y   null null null   2   2       sammy      n    n    y     y     1  3       sameer     n    n    y     n     2  .... 

now when question 1 i.e field q1 =y q2, q3, q4 not asked null, , customer go deptid = 2.

• i.e if q1 = y deptid = 2.
• if q1 = n , q2 = y deptid = 2.
• if q1 = n , q2 = n , q3 = y , q4 = n deptid = 2.
• if q1 = n , q2 = n , q3 = y , q4 = y deptid = 1.
• if q1 = n , q2 = n , q3 = n message should display '' customer not assigned department ''.

note: if q1=n , q2=n , q3=n printing message not necessary

now want check along if given values in table exact , matching

deptid

i have used below code:

 select p.custid (select custid,q1,q2,q3,q4,  case  when q1='y' 2    when q1='n' , q2='y' 2   when q1='n' , q2='n' , q3='y' , q4='n' 2   when q1='n' , q2='n' , q3='y' , q4='y' 1  when q1='n' , q2='n' , q3='n' 0    end deptid,deptassigned   t1 ) p p.deptid<>p.deptassinged  

please me different query's , let me know if changes in above code