选择上一年度每月预订的所有客户

Question

我必须创建一个sql查询，显示去年每个月进行预订的客户的所有信息，我考虑使用按月分组然后计算组数。

像这样:(我不知道如何计算群组的数量）

Select *

From Cliente 

inner join Persona 

on Cliente.CEDULA = Persona.CEDULA

inner join Reserva

on Cliente.cedula = Reserva.CEDULA

Group BY DATEPART(MONTH, Reserva.FECHAINICIO); 

Answer 1

您是否搜索count()？

Select DATEPART(MONTH, Reserva.FECHAINICIO), count(*)

From Cliente 

inner join Persona 

on Cliente.CEDULA = Persona.CEDULA

inner join Reserva

on Cliente.cedula = Reserva.CEDULA

Group BY DATEPART(MONTH, Reserva.FECHAINICIO); 

Answer 2

尝试使用bellow查询，为client.id_column，date_column

输入相关的列名

Select Month, COUNT(<<client.id_column>>) TotalCount
From Cliente
inner join Persona
on Cliente.CEDULA = Persona.CEDULA
inner join Reserva
on Cliente.cedula = Reserva.CEDULA
where  Reserva.<<date_column>>  >= '2017-01-01' 
AND     Reserva.<<date_column>>  <= '2017-12-31'
GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, Reserva.<<date_column>>), 0), as Month; 

Answer 3

假设cedula标识了客户端，则不需要所有连接。然后关键是日期算术部分和聚合：

select r.cedula
from Reserva r
where r.fechainicio >= trunc(sysdate, 'YYYY') - interval '1' year and
      f.fechainicio < trunc(sysdate, 'YYYY')
group by r.cedula
having count(distinct trunc(r.fechainicio, 'MM')) = 12;