There are many standards for EDI and within each standard a distinct definition for each type of file. Which type of file are you trying to import ? An Order, an Invoice, etc.
A file definition includes the definition of each type of line - for instance, an invoice header/master, a list of invoice item lines, etc. So an EDI file is a collection of lines of different format. Merely dumping each line into a table consisting of a varchar(128) column will not be very useful in itself. An incoming Purchase Order file would have to interpreted to put the Buyer Name, order date into a "PO_Header" table, the item lines would have to be extracted to go into a "PO_Detail" table. Then you would have to check against each item in the PO against your own database of items to check for errors on the part of the customer, check prices, etc.
Short of buying a commercial package, parsing multiple types of incoming EDI files is far from being a trivial effort.