窗口函數之range的用法（讀書筆記三）

--RANGE的具體用法

SELECT
emp_id,emp_name,dept_id,hire_date,salary,
--首先按dept_id進行分組，其次按照hire_date進行排序，然後再把入職時間小於等於自身的所有員工薪資進行累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date) sum_salary_part_order,
--按照dept_id進行分組，並統計該部門下所有員工的薪資
SUM(salary) OVER(PARTITION BY dept_id) sum_salary_part,
--直接按照hire_date進行分組，再把入職時間小於等於自身的所有員工薪資進行累計
SUM(salary) OVER(ORDER BY hire_date) sum_salary_order,
--後面均爲首先按dept_id進行分組，其次按照hire_date進行排序，且所有統計不能跨越其所在分區，故不再重複
--且由於是邏輯範圍，因此在PRECEDING和FOLLOWING的表達式上是有符號的
--窗口範圍爲該分區的第一行和該分區的最後一行，與sum_salary_part等同，在非條件表達式中等同於rows
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) sum_1,
--窗口範圍爲該分區的第一行和本行，與sum_salary_part_order等同，在非條件表達式中等同於rows
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) sum_2,
--窗口範圍爲該分區內小於本記錄hire_date-365天的所有的薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN UNBOUNDED PRECEDING AND 365/*value_expr*/ PRECEDING) sum_3,
--窗口範圍爲該分區內小於本記錄hire_date+365天的所有的薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN UNBOUNDED PRECEDING AND 365/*value_expr*/ FOLLOWING) sum_4,
--窗口範圍爲本行和該分區的最後一行，統計的是大於等於本記錄hire_date之後的所有薪資，在非條件表達式中等同於rows
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING) sum_5,
--窗口範圍是本行，所以與本行薪資一樣
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN CURRENT ROW AND CURRENT ROW) sum_6,
--窗口範圍爲該分區內本記錄起和小於本記錄hire_date+365天的所有的薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN CURRENT ROW AND 365/*value_expr*/ FOLLOWING) sum_7,
--窗口範圍爲該分區內大於本記錄hire_date—365天和該分區最後一行的所有薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 365/*value_expr*/ PRECEDING AND UNBOUNDED FOLLOWING) sum_8,
--窗口範圍爲該分區內大於本記錄hire_date-365天，並且截止到當前記錄的所有的薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 365/*value_expr*/ PRECEDING AND CURRENT ROW) sum_9,
--窗口範圍爲該分區的本行current_value-value_expr1到本行current_value-value_expr2的累計，強調value_expr1>=value_expr2
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 365/*value_expr1*/ PRECEDING AND 30/*value_expr2*/ PRECEDING) sum_10,
--窗口範圍爲該分區的本行current_value-value_expr1到本行current_value+value_expr2的累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 365/*value_expr*/ PRECEDING AND 30/*value_expr*/ FOLLOWING) sum_11,
--窗口範圍爲該分區內大於本記錄hire_date+365天的所有的薪資累計
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 365/*value_expr*/ FOLLOWING AND UNBOUNDED FOLLOWING) sum_12,
--窗口範圍爲該分區的本行current_value+value_expr1到本行current_value+value_expr2的累計，本例爲本行後1行和後2行的累計，強調value_expr1<=value_expr2
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE BETWEEN 30/*value_expr1*/ FOLLOWING AND 365/*value_expr2*/ FOLLOWING) sum_13,
--窗口範圍爲該分區的第一行，結束行默認本行，與sum_salary_part_order,sum_2等同，在非條件表達式中等同於rows
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE UNBOUNDED PRECEDING) sum_14,
--窗口範圍僅爲當前行，所以與本行薪資一樣，與sum_6一樣，在非條件表達式中等同於rows
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE CURRENT ROW) sum_15,
--窗口範圍爲該分區內大於本記錄hire_date-365天，並且截止到當前記錄的所有的薪資累計，與sum_9等價
SUM(salary) OVER(PARTITION BY dept_id ORDER BY hire_date 
RANGE 365/*value_expr*/ PRECEDING) sum_16
FROM employeeinfo
ORDER BY dept_id,hire_date;