0 votes 0 votes #plz check 3rd statement: Databases made-easy-test-series databases relational-algebra + – Hradesh patel asked Dec 6, 2016 edited Mar 4, 2019 by akash.dinkar12 Hradesh patel 620 views answer comment Share Follow See all 7 Comments See all 7 7 Comments reply Gate Mission 1 commented Dec 6, 2016 reply Follow Share 3rd is true if R has only A1,A2....An attributes only if I say there is another attribute other than taken in projection then the statement can be false as condition in selection can be done on that another attribute also. Hence unless R is specified with its attributes we cannot comment on this. 1 votes 1 votes Hradesh patel commented Dec 6, 2016 reply Follow Share @Gate mission according to u its true or false??? but according to me its false 0 votes 0 votes Gate Mission 1 commented Dec 6, 2016 reply Follow Share @hradesh how can we say unless we are told about attribs of R . Say R has A,B and C attribs. Project a,b (Selectionc=3 (R)) not equal to Selectionc=3 (Project a,b(R)) [Here predicate involves c attribute] For above it's false ... but now if you change predicate like a=b... then it'll be true.. So we can't say true/false here unless we are specified about predicate relation and attributes of R. 0 votes 0 votes Hradesh patel commented Dec 6, 2016 reply Follow Share it false because here in 3 rd statement in left side relation Ao is allowed but right side its not allowed because here projected A1, A2 ...An. 0 votes 0 votes Jason GATE commented Jan 7, 2017 reply Follow Share 3 rd is false as there , Standard Form is compared with Non Standard Form. 0 votes 0 votes Hradesh patel commented Jan 7, 2017 reply Follow Share how?? 0 votes 0 votes Jason GATE commented Jan 7, 2017 reply Follow Share Observe LHS it is a Non Standard form of Realational Query. 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes 3 rd is false as in it , Standard Form is compared with Non Standard Form. Jason GATE answered Jan 7, 2017 Jason GATE comment Share Follow See all 0 reply Please log in or register to add a comment.