This is data processing technique where data is processed in real time. This is used when delay in handling data is undesirable. Examples of online data processing systems
are air ticketing system, banking system etc.

Dr. E. F. Codd introduced relational database model.

The back-end database file contains the tables. Other database objects such as queries, forms, reports, macros, modules and the links to the tables in back end are known
as back end database components.

Links of the tables in other databases or files created in Access database so that the data can be viewed and edited in Microsoft Access in addition to the original software.

Field properties and their meaning are described below:Field Size: Maximum number of character or value you can enter in fieldFormat: Format for the field. It gives the layout for the field.Input Mask: A way or pattern of data to be entered.Caption: The label for the fieldDecimal Places: The number of digits to the right of decimal place.Default Value: The value automatically entered for the new record.Validation Rule: An expression that limit the value to be entered in the field.Validation Text: The message to be displayed while user violates the rule when entering data.Required: The data should be entered the field can't be left blank.Allow Zero Length: Permits zero length of stringIndexed: The field is to be indexed. Indexing speeds up the searching & sorting.