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Sunday, June 17, 2007

LOGICAL DATABASE.

What are logical databases? What are the advantages/disadvantages of logical
databases?
Ans :- A Logical Database is a hierarchical structure of tables. Use the GET statement to
process Logical Databases.
- LDB consists of logically related tables grouped together ¬ used for reading and
processing data.
- Advantages = 1. No need of programming for retrieval , meaning for data selection
- 2. Easy to use standard user interface, have check completeness of
user input.

Disadvantages = 1. Fast in case of lesser no. of tables But if the table is in the lowest
level of hierarchy, all upper level tables should be read so performance is slower.

Preparation of the data records by the L.D.B and reading of the data records in
the actual report are accomplished with the command pair.

- Put and Get.

The three main elements of LDB are
- Structure, Selections, Database Program.

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