Hi!
I believe phpMyadmin has a zipping option hasn't it ? This should reduce the size of your large file quite substantially.
If it does not maybe you could "slice" your big table in three sub tables with SQL statements like
select * from big_table into small_table1 where Item_ID < 200
select * from big_table into small_table1 where Item_ID >199 and Item_ID<400 etc ...
I know it is a bit rudimentary but hey ... !
If it works ...
Have fun!
One line at a time ...