Question

I have two table table1 and table2
table1:
id amount
1 394
2 897
2 345
3 123

table2:
id amount
2 876
3 890
3 876
4 908

I need to generate table3. join two table and SUM id wise and show top 30 amount holder.
table3:
id amount
2 2118
3 1889
4 908
1 394

Answer 1

You can get data in followng way:

select table3.id, SUM (table3.amount) AS amount
FROM 
(SELECT * FROM table1 UNION ALL SELECT * FROM table2) table3 
GROUP BY table3.id 

If you want to create table with above data, you can do like this:

CREATE TABLE new_table select table3.id, SUM (table3.amount) AS amount
                       FROM 
                       (SELECT * FROM table1 UNION ALL SELECT * FROM table2) table3 
                       GROUP BY table3.id ;