select a1 a_all from table1
union all
select a2 from table1
union all
select a3 from table1
union all
select a4 from table1
......
union all
select a2 from table1
union all
select a3 from table1
union all
select a4 from table1
......
or select a1 form table union all select a2 from table....
union
select a2 from yourtable
union
select a3 from yourtable
...