1. selet Item ID or Item Name from the combo box and click on Add Item button Item ID and Name will    be display in the data grid view. ID and Name columns are Read only field in the Data gridview
2. If i will click on ADD button all grid view field will be stored in the database table except       quantity and amount. 
3. If i will click on UPDATE button all field will able to update.
4. If i will enter price, discount, tax, quantity based on that amount will be change.
5. discount and tax based on price column only.
6. If i will click on TODAY/MONTH button based on Date column today/month records will be display      on the Gridview.
7. If i will click on DELETE button checked Record only will be delte form the database table
8. SlNo and Date will auto gereated Field.
