We have records in this format:
99 0882300 25 YATES ANTHONY V MAY 01 12 04 123456 12345678
The width is fixed and we need to import it int
I did this for a client a while back and, sad as it may seem, Microsoft Access was the best tool for the job for his needs. It's got support for fixed width files baked in.
Beyond that, you're looking at writing a script that translates the file's rows into something SQL can understand in an insert/update statement.
In Ruby, you could use the String#slice method, which takes an index and length, just like fixed width files' definitions are usually expressed in. Read the file in, parse the lines, and write it back out as a SQL statement.