15 votes 15 votes How many minimum relations required for given ER diagram ? Databases er-diagram databases er-to-relational relational + – targate2018 asked Aug 12, 2017 targate2018 9.0k views answer comment Share Follow See all 36 Comments See all 36 36 Comments reply Show 33 previous comments Doraemon commented Apr 6, 2020 reply Follow Share @Satbir I have a few questions. 1>while converting for ER-model to relational model foreign keys can only point to candidate keys.? 2>if we have a table X(A,B) where A and B are the attributes and A and B form the compound keys,then if we have a table Y(P,Q,R) where R is the foreign key of Y we can have (PQ ) as the foreign key in Y which points to the compund key (AB).? 3>foreign keys cannot point to non-key attributes.right? Please answer. 0 votes 0 votes Satbir commented Apr 6, 2020 reply Follow Share foreign keys point to primary keys , not candidate keys. A candidate key is a key which has the capability to become a primary key, but there is only 1 primary key in a table. https://stackoverflow.com/questions/42268886/how-to-have-a-foreign-key-pointing-to-two-primary-keys 1 votes 1 votes Doraemon commented Apr 6, 2020 reply Follow Share https://csedoubts.gateoverflow.in/16478/self-doubt-dbms-er-diagrams That mean here RELATIONAL MODEL no.1 is correct .right? 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes Minimum Number of tables : Seven 1.E5R6(H,F,I ,J) 2.R3E2(D,E,F) 3.E3(F,G) 4.R1(A,D) 5.E1R1(A,B,C,D) 6.R2(D,D) 7.E4R4(K,L,A) shaktisingh answered Jan 25, 2020 shaktisingh comment Share Follow See all 0 reply Please log in or register to add a comment.