Sqlite创建具有来自不同表的总数的视图

Question

我有3个具有identique结构的表，如下dpt1_taks，dpt2_tasks和dpt3_tasks。这是每一个的结构（4列）：

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      |

谢谢您的帮助和最诚挚的问候。

Answer 1

每个表的结果必须分别计算，然后按日期合并：

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

请参见demo。