Consider Table
R1 R2
actname branch branch
das tsr tsr
das tvm pkd
raju tsr
raju pkd
radha tsr
radha pkd
R1 / R2 means " customers who have account in all branches of bank described in R2 "
Output
raju
radha
Right ?
What if R2 contains 0 tuples ? Will it work ? If so How ?