SELECT field1, field2 FROM table1
1, 'test' 2, 'test2'
SELECT field3, field6 FROM table2
1, 'test3' 2, 'test5'
SELECT field1, field2 FROM table1 UNION SELECT field3, field6 FROM table2
1, 'test' 2, 'test2' 1, 'test3' 2, 'test5'