左连接表与总和 - 导致问题

Question

我正在尝试左连接多个表，其中两个和列都连接在中间步骤表上。

表格如下：

表1

ID  Value1
1   3
2   2
3   3

表2

ID  Value1
1   5
2   2
3   2
4   1

Jointable

ID
1
2
3
4
5
6

我正在尝试输出：

Table1Value1SUM Table2Value1Sum
8 | 10

使用SQL：

SELECT SUM(Table1.Value1) Table1Value1SUM,SUM(Table2.Value1) Table2Value1Sum From Table1
Left Join JoinTable
On JoinTable.ID = Table1.ID
Left Join Table2
On Table2.ID = Table1.ID

我得到了这些结果：

Table1Value1SUM Table2Value1Sum
8 | 9

Answer 1

jointable必须left join与其他2个表格一起使用。

SELECT SUM(Table1.Value1) Table1Value1SUM,SUM(Table2.Value1) Table2Value1Sum 
From JoinTable 
Left Join Table1 On JoinTable.ID = Table1.ID
Left Join Table2 On JoinTable.ID = Table2.ID

Answer 2

Left Join Table2 JoinTable代替Table1

SELECT SUM(Table1.Value1) Table1Value1SUM,SUM(Table2.Value1) Table2Value1Sum From Table1
Left Join JoinTable
On JoinTable.ID = Table1.ID
Left Join Table2
On JoinTable.ID = Table2.ID

Answer 3

有什么可以加入到此？你想要table1和table2的总和，因此：

select
  (select sum(value1) from table1) as table1sum,
  (select sum(value1) from table2) as table2sum

或

select t1.table1sum, t2.table2sum
from
  (select sum(value1) as table1sum from table1) t1
cross join
  (select sum(value1) as table2sum from table2) t2;