Question: Databases Consider the relationship R between two entity sets E_1 and E_2. Let K_1 and K_2 be the sets of key attributes of E_1 and

Databases

Consider the relationship R between two entity sets E_1 and E_2. Let K_1 and K_2 be the sets of key attributes of E_1 and E_2, respectively. [a] Assume that R has no attributes and is one-one between E_1 and E_2. What are the keys for the relation R? [b] If R is one-many from E_1 to E_2, what are the keys for the relation R? [c] If R is many-many between E_1 and E_2, what are the keys for the relation R? [d] If R is many-many between E_1 and E_2 and has an attribute A, what are the keys for the relation R? [e] Assume that R is a multiway relationship between three entity sets E_1, E_2, and E_3, with K_1, K_2, and K_3 as the respective sets of their key attributes. Further, assume that in the E/R diagram there is one arrowhead pointing to and no arrowheads pointing to E_2 and E_3. What are the keys for the relation R? Is the following interpretation correct: "Given E_2 entity and E_3 entity, there is at most one related E_1 entity"? Explain your answer. If incorrect, give the correct interpretation. [f] Continuing; assume that in the E/R diagram there is one arrowhead pointing to E_1, one arrowhead pointing to E_2, and no arrowhead pointing to E_3. What are the keys for the relation R? Is the following interpretation correct: "Given E_3 entity, there is at most one related E_1 entity and at most one related E_2 entity"? Explain your answer. If incorrect, give the correct interpretation. [g] Continuing; assume that in the E/R diagram there is one arrowhead pointing to each of the entity sets. What are the keys for the relation R? [h] Continuing; assume that in the E/R diagram there are no arrowheads pointing to any of the entity sets. What are the keys for the relation R

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