Question

问题是这样，我有一个查询返回该特定日期的日期和计数，但我想要的是那个未出现在该范围内的日期（因为表中不存在），但是零值。

我的疑问是：

     SELECT fechacierre, COUNT(idcliente) as cantidad
     FROM cliente
     WHERE fechacierre BETWEEN DATE_ADD('2017-02-21', INTERVAL -6 DAY) AND '2017-02-21'
     GROUP BY fechacierre

给出这个结果：

------------------------
fechacierre | cantidad
------------------------
2017-02-15  | 3
------------------------
2017-02-17  | 1
------------------------
2017-02-20  | 3
------------------------
2017-02-21  | 2
------------------------

如何获取（2017-02-16），（2017-02-18）和（2017-02-19）的值为0的值？

提前致谢！

Answer 1

您可以生成一个包含所需日期的辅助表，如下所示：

select @rowNum := @rowNum +1, DATE_ADD('2017-02-21', INTERVAL -@rownum DAY) as fechacierre from Any_table_with_some_records, (select @rowNum := 0) t

然后你可以加入

SELECT fechacierre, COUNT(idcliente) as cantidad
FROM cliente
RIGHT JOIN aux ON aux.fechacierre = cliente.fechacierre
WHERE fechacierre BETWEEN DATE_ADD('2017-02-21', INTERVAL -6 DAY) AND '2017-02-21'
     GROUP BY fechacierre

这是一个想法，我没有测试它。

Answer 2

您可以使用具有以下所有日期的表来解决它与RIGHT JOIN：

SELECT fechacierre, COUNT(idcliente) as cantidad
     FROM cliente RIGHT JOIN (select * from 
(select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) selected_date from
 (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
 (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
 (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
 (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
 (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) v
where selected_date between DATE_ADD('2017-02-21', INTERVAL -6 DAY) and '2017-02-21') t ON fechacierre = selected_date
     WHERE fechacierre BETWEEN DATE_ADD('2017-02-21', INTERVAL -6 DAY) AND '2017-02-21'
     GROUP BY fechacierre

使用零值在mysql查询上添加缺少的行

2 个答案: