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详解窗口函数中的RANGE BETWEEN子句

news 2025/10/18 16:19:26

基本语法：

SUM(column) OVER (PARTITION BY partition_expressionORDER BY order_expression [ASC|DESC]RANGE BETWEEN lower_bound AND upper_bound
)

RANGE BETWEEN的边界选项：

UNBOUNDED PRECEDING: 窗口从分区的第一行开始
UNBOUNDED FOLLOWING: 窗口到分区的最后一行结束
CURRENT ROW: 当前行（对于RANGE，它表示与当前行在排序表达式上值相同的所有行）
expression PRECEDING: 在排序表达式上，值比当前行小一定数量的行（该表达式必须是非负常量，并且与排序表达式类型兼容）
expression FOLLOWING: 在排序表达式上，值比当前行大一定数量的行

示例：

1.假设我们有一个销售表sales，包含字段sale_date（日期类型）和amount（销售额）。我们想要计算每个销售记录前7天（包括当天）的累计销售额。

with temp_1 as (
select 
'01' as employee_id ,'2023-01-01' as sale_date ,1000.00 as amount 
union all  
select 
'02' as employee_id ,'2023-01-01' as sale_date ,500.00 as amount 
union all 
select 
'02' as employee_id ,'2023-01-02' as sale_date,800.00 as amount 
union all 
select 
'01' as employee_id ,'2023-01-03' as sale_date,500.00 as amount 
union all 
select 
'03' as employee_id ,'2023-01-03' as sale_date,500.00 as amount 
union all 
select 
'02' as employee_id,'2023-01-04' as sale_date,1200.00 as amount 
union all 
select 
'01' as employee_id,'2023-01-05' as sale_date,500.00 as amount 
union all 
select 
'03' as employee_id,'2023-01-05' as sale_date,700.00 as amount 
union all 
select 
'01' as employee_id,'2023-01-06' as sale_date,600.00 as amount 
union all 
select 
'02' as employee_id,'2023-01-07' as sale_date,720.00 as amount 
union all 
select 
'01' as employee_id,'2023-01-08' as sale_date,1500.00 as amount 
union all 
select 
'03' as employee_id,'2023-01-08' as sale_date,900.00 as amount 
union all 
select 
'01' as employee_id,'2023-01-09' as sale_date,1000.00 as amount 
)SELECTsale_date,amount,SUM(amount) OVER (ORDER BY datediff(sale_date, '1970-01-01')RANGE BETWEEN 6 PRECEDING AND CURRENT ROW) AS running_total,SUM(amount) OVER (ORDER BY CAST(sale_date AS TIMESTAMP) RANGE BETWEEN INTERVAL 6 DAYS PRECEDING AND CURRENT ROW) AS running_total_0
FROM temp_1;

2.假设我们有一个按分数排序的学生成绩表scores，我们想要计算每个学生分数上下10分范围内的平均分（包含当前行）。

sql
SELECTstudent_id,score,AVG(score) OVER (ORDER BY scoreRANGE BETWEEN 10 PRECEDING AND 10 FOLLOWING) AS avg_score_in_range
FROM scores;

注意事项

排序表达式类型：对于RANGE BETWEEN，排序表达式必须是数值类型、日期类型或时间戳类型。如果是日期或时间戳，则边界必须使用INTERVAL来指定；如果是数值，则直接使用数字。
边界定义：RANGE窗口是基于排序表达式的值来确定的。例如，RANGE BETWEEN 10 PRECEDING意味着所有排序表达式值在[当前行值-10, 当前行值]范围内的行（对于数值类型）。
重复值处理：在同一分区内，如果有多行具有相同的排序表达式值，那么它们都会被包含在窗口中。因此，RANGE窗口的大小可能会动态变化，特别是当有重复值时。

与ROWS BETWEEN的区别

ROWS是按物理行数划分窗口，而RANGE是按逻辑值范围划分窗口。
例如，ROWS BETWEEN 2 PRECEDING AND CURRENT ROW会包括当前行及前两行（物理位置上的前两行），而RANGE BETWEEN 2 PRECEDING AND CURRENT ROW会包括所有排序值在[当前值-2, 当前值]范围内的行（可能有更多行，因为值重复或值在范围内）。