1 votes 1 votes σ(x<y) ( π(x,y) R ) Is this type of query valid or should I have selection operator inside the and projection outside or both are same? ankit_thawal asked Jan 29, 2018 ankit_thawal 274 views answer comment Share Follow See 1 comment See all 1 1 comment reply hs_yadav commented Jan 29, 2018 reply Follow Share σ(x<y) ( π(x,y) R ) ........for the present situation it is valid.... 0 votes 0 votes Please log in or register to add a comment.