COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Pi (Greek)
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Sigma (Greek)
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Lambda (Greek)
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Omega (Greek)
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Detailed explanation-1: -Which of the following is used to denote the selection operation in relational algebra? Explanation: The select operation selects tuples that satisfy a given predicate. 4.
Detailed explanation-2: -Select Operation: The select operation selects tuples that satisfy a given predicate. It is denoted by sigma ().
Detailed explanation-3: -Select selects tuples that satisfy a given predicate. Select is denoted by a lowercase Greek sigma ( ), with the predicate appearing as a subscript. The argument relation is given in parentheses following the .
Detailed explanation-4: -Select operation is done by Selection Operator which is represented by “sigma"(). It is used to retrieve tuples(rows) from the table where the given condition is satisfied. It is a unary operator means it require only one operand.
Detailed explanation-5: -The SELECT opeartor is (sigma) symbol and used as an expression to choose tuples that meet the selection condition… <Selection condition>(R) PROJECT. The PROJECT operator in RA is ∏ (pi) symbol used to choose attributes from a relation.