Question - What are logical databases? 
          
        
        Answer - 
        1: -
insert' will add a new record or a new row into the database table. 
'Update' will modify a record in the DB table. 
'Modify' it is a combination of both insert and update... 
2: -
INSERT - Add a new record into the database table. 
MODIFY - If record is available it modifies otherwise it wont modify. 
UPDATE - If record is available its update the record otherwise it creates a new record.