Question

Explain tha differnce between logical and physical data independence

Answer 1

PHYSICAL DATA INDEPENDENCE:

physical storage structure or devices can be changed without affecting conceptual schemaModification are performed to improve performanceIt is not difficult because, we have to only replace the data from one device to another device. No need to change the data only change the location of dataIt provide independence and immunity to conceptual and external schema

LOGICAL DATA INDEPENDENCE:

Conceptual schema can be changed without affecting external schemaWe change/modify conceptual schema when structure of database is alteredIt is very difficult because, we have to see that the relationship must not changing, data is not getting lost and some other factorsIt only provide immunity to external schema and application program.


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