0 votes 0 votes Source Made Easy Test Serires Can anyone please tell me the answer for this, with explaination. According to me it will give the customer who buy from atleast one store, but the answer given is customer who buy from all stores. Databases databases sql + – print asked Jan 21, 2022 print 486 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes @print You forget to add projection operator after (C*S)-B table . That means ∏Cname (C*S-B ) = B,C …. now C - ∏Cname (C*S-B ) = A , as C= (A,B,C ) …. A means customer who buy from all shops. As A S1 A S2 so A is related to shop 1 and shop 2 both .... And shop table has only 2 entries s1 and s2 .... Hence customer who buy from all shops ... 1. https://gateoverflow.in/19246/Tifr2010-b-33 2. https://gateoverflow.in/25872/Tifr2013-b-19 22 answered Feb 23, 2022 22 comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes For these kind of questions it is better to take examples to avoid confusion itachi_Uchiha778 answered Feb 27, 2022 itachi_Uchiha778 comment Share Follow See 1 comment See all 1 1 comment reply `JEET commented Feb 27, 2022 reply Follow Share Right, solving by illustration is always a better choice. 0 votes 0 votes Please log in or register to add a comment.