对比值重复时行号不重复不间断,即返回1,2,3,4,5...,不返回1,2,2,4...dense_rank():返回行号,对比值重复时行号重复但不间断, 即返回1,2,2,3select department,number,wages,--值同排名相同,同时不保留被占用的排名序号,即总排名号不连续rank()over(partition by department order by wages desc)...
<窗口函数> over (partition <用于分组的列名> order by <用于排序的列名>) 1. 2. 2.其他专用窗口函数 专用窗口函数rank, dense_rank, row_number有什么区别呢? select * , rank() over (order by 成绩 desc) as rank, dense_rank() over (order by 成绩 desc) as dense_rank, row_number() over...
empno, salary, rank() OVER (PARTITION BY depname ORDER BY salary DESC) FROM empsalary; depname | empno | salary | rank ---+---+---+--- develop | 8 | 6000 | 1 develop | 10 | 5200 | 2 develop | 11 | 5200 | 2 develop | 9 | 4500 | 4 develop | 7 | 4200 | 5 personn...
over(partition by cno order by degree ) 先对cno 中相同的进行分区,在cno 中相同的情况下对degree 进行排序 over()函数写法over(partition by expr2 order by expr3),根据expr2对结果进行分区,在各分区内按照expr3进行排序; over函数不能单独使用,需要与row_number(),rank()和dense_rank,lag()和lead(),...
partition by只是将原始数据进行名次排列(记录数不变) group by是对原始数据进行聚合统计(记录数可能变少, 每组返回一条) 3. 使用rank over()的时候,空值是最大的,如果排序字段为null, 可能造成null字段排在最前面,影响排序结果。 可以这样: rank over(partition by course order by score desc nulls last) ...
1、rank over () 可以把成绩相同的两名是并列,如下course = 2 的结果rank值为:1 2 2 4 5 selectname, score, course,rank()over(partitionbycourseorderbyscoredesc)asrankfromjinbo.student; name|score|course|rank---+---+---+---dock|100|1|1bob|90|1|2cark|80|1|3elic|70|1|4hill|60|...
3.3 number_rank()查询每一科的学生成绩编号 select row_number() over (PARTITION BY subject order by score),* from t2 ;row_number | id | subject | name | score---+---+---+---+---1 | 26 | article | AA6 | 02 | 2...
OVER子句定义了窗口函数的作用范围和排序规则。它告诉PostgreSQL如何处理查询中的行,以便窗口函数能够正确地执行其计算。OVER子句可以包含PARTITION BY和ORDER BY子句,分别用于分组和排序。 2. PARTITION BY在窗口函数中的用途 PARTITION BY用于将结果集分成多个分区(或组)。在每个分区内,窗口函数将独立地执行其计算。这...
SELECTd.department_name"部门名称",concat(e.first_name,',',e.last_name)"姓名",e.salary"月薪",ROW_NUMBER()OVER(PARTITIONBYe.department_idORDERBYe.salaryDESC)AS"row_number",RANK()OVER(PARTITIONBYe.department_idORDERBYe.salaryDESC)AS"rank",DENSE_RANK()OVER(PARTITIONBYe.department_idORDERBYe....
dense_rank() 返回行号,对比值重复时行号重复但不间断,即返回1,2,2,3... postgres=# select dense_rank() over(partition by begincity order by pubtime),* from bills; dense_rank | id | goodsdesc | beginunit | begincity | pubtime | amount ---+---+---+---+---+---+--- 1 ...