I have three columns in the first table, the second table have one column that exists in the first table and 2 I want to add.
select c1 as col1, c2 as col2, c3 as col3
select c1, c4 as col4, c5 as col5
null or any other default value you like as static column
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