你可以试试这个-

select A.Date, 
       COALESCE(count(key1),0), 
       COALESCE(count(key2),0), 
       COALESCE(count(key3),0)
FROM TableA A 
LEFT JOIN TableB B on A.Date = B.Date 
LEFT JOIN TableC C on A.Date = C.Date
LEFT JOIN TableD D on A.Date = D.Date
Group by A.Date;

我使用左连接而不是内连接，因为我们需要表a中的所有数据。第一列也应该来自表a，即驱动程序表。

在子查询中进行连接，然后进行分组，例如。，

with join_table as (select COALESCE(TableB.Date, TableC.Date, TableD.Date) as Date, 
    key1, key2, key3
    FROM TableA A JOIN TableB B on A.Date = B.Date 
    JOIN TableC C on A.Date = C.Date
    JOIN TableD D on A.Date = D.Date
)
select Date,
       COALESCE(count(key1),0), 
       COALESCE(count(key2),0), 
       COALESCE(count(key3),0)
  from join_table
 group by Date

实际上，不需要在内部连接中合并连接键。

我想你在寻找完全的外部连接。下面是示例代码

select COALESCE(a.Date, b.Date, c.Date,d.Date), 
       COALESCE(sum(key1),0), 
       COALESCE(sum(key2),0), 
       COALESCE(sum(key3),0)

(select distinct date as date from tableA ) as a
full outer join 
(select  date ,sum(key1) as key1 from tableB group by date) as b
on a.date=b.date
full outer join
(select  date ,sum(key2) as key2 from tableB group by date) as c
on a.date=c.date
full outer join
(select  date ,sum(key3) as key2 from tableB group by date) as d
on a.date=d.date
Group by COALESCE(a.Date, b.Date, c.Date,d.Date);`