如何计算 sql 中的重复数

Question

我有如下表我想计算重复并分配它们。

customer date       type
A       2020/8/1     a
A       2020/8/1     b
B       2019/5/1     a
B       2019/6/1     c

我想count customer和date中的重复，分配它们的duplicate数量。

["customer,"date"]

customer date     type     duplicate
A       2020/8/1   a       2
A       2020/8/1   b       2
B       2019/5/1   a       1
B       2019/6/1   c       1

如果有人有意见分配重复的行数。 请告诉我。 谢谢

Answer 1

使用count() over分析 function。 Date是保留字

SELECT c.*,
       COUNT(*) OVER (PARTITION BY "customer","date") duplicate 
FROM   tablename c;

如果你想格式化日期列

SELECT "customer",
        to_char("date",'DD-MON-YYYY HH:MI:SS AM') "date",
        "type",
       COUNT(*) OVER (PARTITION BY "customer","date") duplicate 
FROM tablename ;

Answer 2

你可以试试下面的 -

select a.customer,a.date,type,duplicate 
from tablename a
join 
(select customer,date, count(*) as duplicate from tablename group by customer, date) b 
on a.customer=b.customer and a.date=b.date