convert rows ro collumns

I have this data, where number of rows can be different:

select '' col1 union  allselect 'asd'   union  allselect 'gfrf2'   union  allselect '2_44ff'   union  allselect 'ae6754'   union  allselect 'fff'   union  allselect 'zzzz'  order by 1

Need to get this result:

select '', '2_44ff','ae6754','asd','fff','gfrf2','zzzz'