在上面的示例中,rows between 2 preceding and current row 定义了窗口函数 AVG 的作用范围。对于每个月的支付金额,窗口函数将计算包括当前月在内的前三个月的平均支付金额。例如,如果当前月是3月,那么窗口函数将计算1月、2月和3月的平均支付金额。
UNBOUNDED PRECEDING: 从窗口的第一行开始。 CURRENT ROW: 当前行。 UNBOUNDED FOLLOWING: 到窗口的最后一行。 基本语法示例 SELECT class_id, student_id, score, RANK() OVER (PARTITION BY class_id ORDER BY score DESC) AS rank FROM student_scores; 简单例子 先通过下面的代码,构造一个简单的数据库: dr...
1.“rows between unbounded preceding and current row” 功能可实现与lead类似功能,但使用较为复杂,没lead好理解; 2.“rows between unbounded preceding and current row”与lead不同之处在于lead最后一条数据为NULL; 3.“rows between unbounded preceding and current row”、lead、以及IoT数仓中delta函数均可实...
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW(表示从起点到当前行) ROWS BETWEEN 2 PRECEDING AND 1 FOLLOWING(表示往前2行到往后1行) ROWS BETWEEN 2 PRECEDING AND 1 CURRENT ROW(表示往前2行到当前行) ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING(表示当前行到终点) 1. 2. 3. 4. 5. 6. 7....
Oracle为这种情况提供了一个子句:rows between ... preceding and ... following。从字面上猜测它的意思是:在XXX之前和XXX之后的所有记录,实际情况如何让我们通过示例来验证: SQL > select month , 2 sum (tot_sales) month_sales, 3 sum ( sum (tot_sales)) over ( order by month ...
CURRENT ROW:窗口包括当前行 value PRECEDING:窗口从当前行向前value行开始 value FOLLOWING:窗口从当前行向后value行结束 示例: selectname,date,timestamp,number,-- 前1行_当前行sum(number)over(partitionbynameorderbytimestamprowsbetween1precedingandcurrentrow)assum_number_w1_row,-- 前1行_后1行sum(number...
妙用窗口函数 rows between 、range between function(x)over(partitionbyxxxbyxxrowsbetween6precedingandcurrentrow) 另有,from:rows between unbounded preceding and current row等,unbounded ,preceding ,following,current row含义详解_卡奥斯道的博客-CSDN博客...
让我们使用一个使用两个窗口定义的示例：ORDER BY x ROWS BETWEEN 2 PRECEDING AND CURRENT ROWORDER ...
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW -- 第一行 - 当前行 ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING -- 当前行 - 最后一行 ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING -- 第一行 - 最后一行 1. 2. 3. 4.
(ROWS | RANGE) BETWEEN CURRENT ROW AND (CURRENT ROW | (UNBOUNDED | [num]) FOLLOWING) 区别 ROWS BETWEEN 3 PRECEDING AND 4 FOLLOWING:表示在当前顺序的前提下,往前3行数据和往后4行数据,总计8行,当然这个8行不是绝对的,比如排序后的第一条数据亦或排序后的最后一条数据,根据行数判定肯定不会是8行。