如何使用SQL中的联接检索数据

Question

我正在寻找这样的事情：

Table 1:

Column-A  C-B C-C
1          1   1
2          5   2
4          3   2

Table 2:

Column-D  C-E 
1          3 
7          9  
6          5  


result set:


1   1
2   5
4   3
1   3
7   9
6   5

Answer 1

select columnA, C-b from table1
union all
select columnD, C-E from table2

Answer 2

试试这个

           select column1,column2 from tablename1
          union all 
          select column3,column4 from tablename2