efficient way to store text file line by line

Hi,
we want to store a text file with test data line by line in a sql db.
Later on it should be possible to insert new lines easily.
An easy solution would be that each row in the db has an order number and
then when inserting every following line has to be increased, but that seems slow and awkward. We then though about using floats as order numbers, so that it is easy to increase an existing order number without "renaming" the rest, but this might lead to problems with rounding errors.
Another idea was kind of a linked list, each row contains the id of the previous and next, so that when inserting an entry, three rows have to be changed.

Does anybody have a better idea?