I. True - Self-join is indeed possible in SQL with table alias. This is a common practice when you want to combine rows with other rows in the same table when there's a match based on some condition.

II. False - The basic operations in relational algebra are select, project, union, set difference, Cartesian product, and rename. Outer join is not considered a basic operation.

III. False - Natural join and outer join operations are not equivalent. A natural join is a type of join that creates a new result table by combining column values of two tables based on the join-predicate. The query compares each row of table1 with each row of table2 to find all pairs of rows which satisfy the join-predicate. While an outer join does not require each record in the two joined tables to have a matching record. The joined table retains each record—even if no other matching record exists.

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I. True - Self-join is indeed possible in SQL with table alias. This is a common practice when you want to combine rows with other rows in the same table when there's a match based on some condition.

II. False - The basic operations in relational algebra are select, project, union, set difference, Cartesian product, and rename. Outer join is not considered a basic operation.

III. False - Natural join and outer join operations are not equivalent. A natural join is a type of join that creates a new result table by combining column values of two tables based on the join-predicate. The query compares each row of table1 with each row of table2 to find all pairs of rows which satisfy the join-predicate. While an outer join does not require each record in the two joined tables to have a matching record. The joined table retains each record—even if no other matching record exists.

Knowee AI · Accepted Answer

I. True - Self-join is indeed possible in SQL with table alias. This is a common practice when you want to combine rows with other rows in the same table when there's a match based on some condition.

II. False - The basic operations in relational algebra are select, project, union, set difference, Cartesian product, and rename. Outer join is not considered a basic operation.

III. False - Natural join and outer join operations are not equivalent. A natural join is a type of join that creates a new result table by combining column values of two tables based on the join-predicate. The query compares each row of table1 with each row of table2 to find all pairs of rows which satisfy the join-predicate. While an outer join does not require each record in the two joined tables to have a matching record. The joined table retains each record—even if no other matching record exists.

Which of the following is true? I. Implementation of self-join is possible in SQL with table alias.II. Outer-join operation is the basic operation in relational algebra. III. Natural join and outer join operations are equivalent.

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