generate data to a files
format of the data files:
1 , 2,3 represent the transaction num
in transaction 1 have 3 items there are Apples, Oranges, Pear..
So user can key in all them they want, then the system generate the transaction based on the item that user key in. And the user need to set the number of the transaction they want. like 1000, 100000 and any values