0 votes 0 votes Given answer: B I don't know how to deal with NULL in such query operations. Please explain. Databases sql databases + – shikharV asked Dec 8, 2015 • retagged Dec 8, 2015 by shikharV shikharV 1.1k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
3 votes 3 votes NULL = unknown unknown AND True = unknownunknown AND False = False unknown AND unknown = unknown unknown OR True = Trueunknown OR False = unknown unknown OR unknown = unknown So according to me answer is option B) A and C are selected. Umang Raman answered Dec 8, 2015 Umang Raman comment Share Follow See all 2 Comments See all 2 2 Comments reply shikharV commented Dec 8, 2015 reply Follow Share Can you explain why B row is not the part of output? 0 votes 0 votes Umang Raman commented Dec 8, 2015 reply Follow Share Dbms marks> seminar marks AND seminar mark > 75 AND (dbms mark > 90 ) or dbms mark <50 unknown > 90 AND 90 >75 AND unknown >90 or unknown < 50 unknown AND True AND Unknown OR unknown = unknown so its not selected. 0 votes 0 votes Please log in or register to add a comment.