0 votes 0 votes Why option d is incorrect? Databases databases + – Avik Chowdhury asked Aug 14, 2018 Avik Chowdhury 436 views answer comment Share Follow See all 3 Comments See all 3 3 Comments reply Shaik Masthan commented Aug 14, 2018 reply Follow Share please type the question.... it is not clearly visible 0 votes 0 votes Shubhgupta commented Aug 14, 2018 reply Follow Share Last one is not right because it is joining those rows of R1 with R2 which are not having R = S. 0 votes 0 votes rajatmyname commented Sep 6, 2018 reply Follow Share The answer given is correct. 0 votes 0 votes Please log in or register to add a comment.
Best answer 0 votes 0 votes R1 P Q R a b 1 c d 2 R2 S T 1 e 2 f 3 g R1 JOIN R2 WHERE R $\neq$ S P Q R S T a b 1 2 f a b 1 3 g c d 2 1 e c d 2 3 g Now if we SELECT R from this join we will still get {1,2}. So, it doesn't produce an empty relation. jhaanuj2108 answered Aug 14, 2018 selected Aug 15, 2018 by Avik Chowdhury jhaanuj2108 comment Share Follow See all 0 reply Please log in or register to add a comment.