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Window functions

Window functions perform calculations using values from multiple rows to produce a value for each row separately. Window functions can only be calculated once the entire table is read.

You can use window functions to perform operations such as:

• Comparing an individual number value in a row with the average, maximum, or minimum within the column.

• Calculating the rank of an individual value, either within the column or within the entire table.

Window functions do not change the number of records in the table but can perform similar tasks as aggregation functions or relational functions and range functions.

使用每個函數中的下拉式功能表，以查看每個函數的簡要描述及語法。按一下語法描述中的函數名稱，以取得進一步詳細資料。

Window

The Window function performs calculations from multiple rows, producing a value for each row separately.

window(main_expr, [partition1, partition2, ...], [sort_type, [sort_expr],[filter_expr], [start_expr, end_expr]])

WRank

The WRank function performs ranking calculations inside Window.

wrank([mode[, fmt]])