SQL查询返回表A中的所有结果，并且仅返回表B中的未包含在表A中的结果

Question

I am trying to query two tables and return a single result set that includes all values from table A and only values from Table B that are not included in Table A.

Table A        Table B
ID  Name       ID  Name
A   John       C   Drew
B   Jacob      D   Shane
C   Nancy

Based on the ID column, result set should be:

ID  Name
A   John
B   Jacob
C   Nancy
D   Shane

I would exclude ID C from Table B from the result set because table A has a record with an ID of C.

Does anyone know how I would begin to accomplish this?

Answer 1

You can do this as using union all and not exists :

select a.id, a.name
from a
union all
select b.id, b.name
from b
where not exists (select 1 from a where a.id = b.id);