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Does Selection algebra operator in Relational algebra removes duplicates from the tuples. Because when I am studying the definition of projection operator then there it's explicitly given that it removes duplicates. Consider for example if in my relational algebra R dataset I have 2 columns A and B which is given here. I know selection algebra operator doesn't printout anything...but I want to know how it works internally...whether it removes duplicates tuples or not..? Also firstly do such repititions in relational algebra dataset allowed ..?

Piyush Sawarkar
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1 Answers1

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This answer is coming late, anyway...

A relation is a set and so it has no duplicates. This means that selection eliminates duplicates.

However, note that database systems that represent relations as tables may not eliminate duplicate rows.

You can read more in the Wikipedia article on database tables.

Mubaraq Wahab
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  • Highlighting a line from the wiki reference. a table is usually a multiset (bag) of rows where a relation is a set and does not allow duplicates – Giteshwar Mali Jan 03 '24 at 14:00