0 votes 0 votes If (sname,ssub,spart) are composite primary key then can we take null or dublicate value in ssub or in any single attribute in above composite key? learner_geek asked Jun 10, 2017 edited Jun 10, 2017 by learner_geek learner_geek 186 views answer comment Share Follow See all 2 Comments See all 2 2 Comments reply Akriti sood commented Jun 10, 2017 reply Follow Share https://stackoverflow.com/questions/25531765/can-prime-attributes-have-null-values 0 votes 0 votes Rupendra Choudhary commented Jun 10, 2017 reply Follow Share I don't think if there is some restriction on particular entry of composite primary key. I think some part can be NULL unless the rows are uniquely distinguishable. Although prefer not to set any entry null. tell me if my consideration is wrong. 0 votes 0 votes Please log in or register to add a comment.