oracle search columns in schema

1select t.owner as schema_name,
2       t.table_name , col.column_name
3from sys.all_tab_columns col
4inner join sys.all_tables t on col.owner = t.owner 
5                              and col.table_name = t.table_name
6where col.column_name = ''
7and col.owner not in ('')
8order by col.owner, 
9         col.table_name;