Number-Systems
August 9, 2024Routing
August 9, 2024Database-Management-System
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Question 893
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Which operation is used to extract specific columns from a table?
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Project
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Join
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Extract
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Substitute
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Question 893 Explanation:
Projection (π)
Projection is used to project required column data from a relation. By Default projection removes duplicate data.
Example :
R(A B C)
———-
1 2 4
2 2 3
3 2 3
4 3 4
π (BC)
B C
—–
2 4
2 3
3 4
Projection is used to project required column data from a relation. By Default projection removes duplicate data.
Example :
R(A B C)
———-
1 2 4
2 2 3
3 2 3
4 3 4
π (BC)
B C
—–
2 4
2 3
3 4
Correct Answer: A
Question 893 Explanation:
Projection (π)
Projection is used to project required column data from a relation. By Default projection removes duplicate data.
Example :
R(A B C)
———-
1 2 4
2 2 3
3 2 3
4 3 4
π (BC)
B C
—–
2 4
2 3
3 4
Projection is used to project required column data from a relation. By Default projection removes duplicate data.
Example :
R(A B C)
———-
1 2 4
2 2 3
3 2 3
4 3 4
π (BC)
B C
—–
2 4
2 3
3 4