SELECT operation in SQL is equivalent to

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SELECT operation in SQL is equivalent to

1. the selection operation in relational algebra
2. the selection operation in relational algebra, except that SELECT in SQL retains duplicates
3. the projection operation in relational algebra
4. the projection operation in relational algebra, except that SELECT in SQL retains duplicates

Correct Option: D

SELECT operation in SQL perform vertical partitioning which is made by projection operation in relational calculus, but SQL is multi-sets. Hence the projection operation in relational algebra, except that SELECT in SQL retains duplicates answer is correct.