使用零值在mysql查询中添加缺少的行

问题是，我有一个查询，返回一个日期和该特定日期的计数，但我想要的是，不在该范围内（因为表中不存在）的日期显示为零值

我的问题是：

     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
------------------------

如何获得（2017-02-16）、（2017-02-18）和（2017-02-19）的0值

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提前谢谢

您可以生成包含所有所需日期的辅助表，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

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

那你就可以直接加入了

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，我没有对它进行测试。

您可以通过使用一个表进行正确的连接来解决它，该表具有如下所有日期：

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

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

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这是在调用SQL的代码中应该做的事情，比如php或在服务器上运行的任何东西。这可以在SQL中完成，但您需要另一个表，其中每个日期的行数在范围内。