2 votes 2 votes Say I have two tables and they have some attributes in common, assume x is common, now will x will appear once in the output or twice for following cases? Natural join Cross product Conditional join Please explain. Databases natural-join databases relational-algebra + – rahul sharma 5 asked Jan 5, 2017 rahul sharma 5 973 views answer comment Share Follow See 1 comment See all 1 1 comment reply thor commented Jan 5, 2017 reply Follow Share Once in natural join and twice in others 0 votes 0 votes Please log in or register to add a comment.
Best answer 4 votes 4 votes $R$ A B 1 2 1 3 2 1 $S$ A C 1 3 2 3 2 4 Case I) $R\Join S$ A B C 1 2 3 1 3 3 2 1 3 2 1 4 Case II) $R\times S$ A B A C 1 2 1 3 1 2 2 3 1 2 2 4 1 3 1 3 1 3 2 3 1 3 2 4 2 1 1 3 2 1 2 3 2 1 2 4 Case III) $R\Join _{A>1 } S$ A B A C 2 1 1 3 2 1 2 3 2 1 2 4 santhoshdevulapally answered Jan 5, 2017 selected Nov 22, 2018 by Lakshman Bhaiya santhoshdevulapally comment Share Follow See all 0 reply Please log in or register to add a comment.