具有不同列數的聯盟

Question

我在第一個表中有三列，第二個表有一列存在於第一個表中，2列我想要添加。

例如：

select  c1 as col1, c2 as col2, c3 as col3
from    Table1
union
select  c1, c4 as col4, c5 as col5
from    Table2

expected Result:

col1,col2,col3,col4,col5

Answer 1

只需添加null或您喜歡的任何其他默認值作為靜態列

select  c1 as col1, 
        c2 as col2, 
        c3 as col3, 
        null as col4, 
        null as col5
from    Table1
union
select  c1, 
        null, 
        null, 
        c4,
        c5
from    Table2 

Answer 2

您已經問過這個問題，並得到了答案 - https://stackoverflow.com/questions/18923218/unioning-tables-with-different-number-of-columns/18923250#18923250 。 是否有可能實際上你需要一個聯合 ，而不是聯盟：

select
    t1.c1 as col1,
    t1.c2 as col2,
    t1.c3 as col3,
    t2.c4 as col4,
    t2.c5 as col5
from Table1 as t1
    inner join Table2 as t2 on t2.col1 = t1.col1