在具有相同名称的列的表上聚合SQL查询

Question

I have two tables, both with a column called transaction_amnt . Is there a way I can write a SQL query that returns the sum of all of the transaction amounts in both tables? I tried

select sum(transaction_amnt) from table1 natural join table2;

but, I'm thinking that join isn't really what I want here.

Answer 1

I guess union all best fits to your question as it will not remove duplicates on the records.

SELECT SUM(x.transaction_amnt) totalAmount
FROM
(
    SELECT transaction_amnt from table1
    UNION ALL
    SELECT transaction_amnt from table2
) x

Answer 2

As you did not show us your table definition it is not clear to me what you really want, but this might what I think you are looking for:

select sum(transaction_amnt) 
from (
  select transaction_amnt
  from table1 
  union 
  select transaction_amnt
  from table2
) t