COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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There is not one-you must include a window frame
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ROWS BETWEEN CURRENT ROW AND CURRENT ROW
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RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
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ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
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Detailed explanation-1: -UNBOUNDED PRECEDING is the default. CURRENT ROW indicates the window begins or ends at the current row. UNBOUNDED FOLLOWING indicates that the window ends at the last row of the partition; offset FOLLOWING indicates that the window ends a number of rows equivalent to the value of offset after the current row.
Detailed explanation-2: -ORDER BY is optional for the aggregate window functions and required for the ranking functions. This ORDER BY clause does not relate to the ORDER BY clause used outside of the OVER clause. The window function is applied to the rows within each partition sorted according to the order specification.
Detailed explanation-3: -FRAME clause is used with window/analytic functions in SQL. Whenever we use a window function, it creates a ‘window’ or a ‘partition’ depending upon the column mentioned after the ‘partition by’ clause in the ‘over’ clause.
Detailed explanation-4: -UNBOUNDED PRECEDING Specify UNBOUNDED PRECEDING to indicate that the window starts at the first row of the partition. This is the start point specification and cannot be used as an end point specification. UNBOUNDED FOLLOWING Specify UNBOUNDED FOLLOWING to indicate that the window ends at the last row of the partition.