All major DBMS provide file import utility. where you can spceify datatypes/ field separator and record seprators.
Look at your all sources, and find all distinct columns and create table in your destination database with all columns you found in all sources
then case by case (file format by file format), import your files to the new table using import tool
if you using oracle as destination table, you can also take help of sqldeveloper (u can download from oracle website for free). It has facility to import several file formats.