It may not have much things to do with table structure.
I'm worried because of this ...
suppose Excel data contains some SPACES ...and after import this SPACE goes to the CELL.
I don't want this extra SPACE damage my joined update query. ...now I have two choices to get rid of this space..
(a) just need a TRIM to work ....I asked the same for this .....This could be a solution also.
(b) remove SPACE from the EXCELL cell itself so that after import into table there will no SPACE in the CELL.... but unfortunately I don't know how to remove SPACE from Excel cell ....Do you know this ? This could be a solution also