COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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OVER
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SUBGROUP
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PARTITION BY
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SECTION
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Detailed explanation-1: -A window function computes a value for each row in the window. PARTITION BY expr list PARTITION BY is an optional clause that subdivides the data into partitions. Including the partition clause divides the query result set into partitions, and the window function is applied to each partition separately.
Detailed explanation-2: -They reduce the result set based on the aggregation. Window partitions can be defined to form groups of rows. They compute a value for each and every row in the window. They require the ‘over’ clause.
Detailed explanation-3: -Basic windowing syntax. The usual suspects: SUM, COUNT, and AVG. ROW NUMBER() RANK() and DENSE RANK()
Detailed explanation-4: -The reason why window functions are not allowed in GROUP BY is the order of operations in SQL. The clauses of a SQL query are processed in a different order than they are written in the query.