Sqlite 使用来自不同表的总计创建视图答案

【问题标题】：Sqlite create view with totals from different tablesSqlite 使用来自不同表的总计创建视图
【发布时间】：2019-12-01 11:36:15
【问题描述】：

我有 3 个具有 identique 结构的表，如下 dpt1_taks、dpt2_tasks 和 dpt3_tasks。这是每个（4列）的结构：

id | task_date | assigned | done
_________________________________
1  |01-11-2019 |     x    |  x
2  |01-11-2019 |     x    |     
3  |01-11-2019 |     x    |  x
1  |02-11-2019 |          |
1  |02-11-2019 |     x    |  x
1  |03-11-2019 |     x    |
1  |03-11-2019 |          |
1  |03-11-2019 |     x    |
1  |04-11-2019 |     x    |  x

如何创建一个 sqlite 视图，将每个表的每个日期的 count 分组如下：

DATE      | dpt1_assigned | dpt1_done | dpt2_assigned | dpt2_done |dpt3_assigned | dpt3_done |
_______________________________________________________________________________________________
01-11-2019|       3       |      2    |        5      |      3    |      4       |    0      |
02-11-2019|       1       |      1    |        5      |      3    |      4       |    0      |

提前感谢您的帮助和问候。

【问题讨论】：

标签： sqlite view count

【解决方案1】：

每个表的结果必须单独计算，然后按日期连接：

with 
  dates as (
    select task_date from dpt1_taks union  
    select task_date from dpt2_taks union
    select task_date from dpt3_taks 
  ),  
  cte1 as (
    select task_date,
      coalesce(sum(assigned = 'x'), 0) dpt_assigned,
      coalesce(sum(done = 'x'), 0) dpt_done
    from dpt1_taks
    group by task_date
  ),  
  cte2 as (
    select task_date,
      coalesce(sum(assigned = 'x'), 0) dpt_assigned,
      coalesce(sum(done = 'x'), 0) dpt_done
    from dpt2_taks
    group by task_date
  ),
  cte3 as (
    select task_date,
      coalesce(sum(assigned = 'x'), 0) dpt_assigned,
      coalesce(sum(done = 'x'), 0) dpt_done
    from dpt3_taks
    group by task_date
  )

select d.task_date,
  c1.dpt_assigned dpt_assigned1, c1.dpt_done dpt_done1,
  c2.dpt_assigned dpt_assigned2, c2.dpt_done dpt_done2,
  c3.dpt_assigned dpt_assigned3, c3.dpt_done dpt_done3
from dates d
left join cte1 c1 on c1.task_date = d.task_date
left join cte2 c2 on c2.task_date = d.task_date
left join cte3 c3 on c3.task_date = d.task_date

请参阅demo。

【讨论】：