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Some Database questions

Normalization is a set of rules used for the design of database tables and table are meant to be connected through relation ship. This set of rules are know as normalization. Normalization will avoid the repetitive entries, reduces the storage space, will avoid the need to restructure the table to accommodate new data. By doing the normalization you can increase the speed and flexibility of queries, summaries etc.

Data must be broken into the smallest unit as possible and should not contain any repetitive group of fields.

ID      Name                 Pet1   Pet2     Hours  Days  TotalHours/Week
1       Adarsh Soman    Cat    Cat2      5         5        25

Here name can be broken as first name and last name and pet repeating. So based on the first normal form the table will become as

ID      First Name      LastName  Pet    Hours  Days  TotalHours/Week
1        Adarsh           Soman       Cat       5         5        25

Each non key field should be fact about the field in the primary key. Here pet can be moved into a different table

ID      First Name      LastName  PetID    Hours  Days  TotalHours/Week
1        Adarsh           Soman       1           5         5        25

PetID  PetName
1         Cat
2         Dog

A non-key field should not depend upon the other non key field. Here 
In the above table TotalHours/Week is calculated by multiplying hours into days.(total=hours*days). So based on the third normal form we can remove it.

ID      First Name      LastName  PetID    Hours  Days  
1        Adarsh           Soman       1           5         5        

Process of putting one fact in numerous place is know as denormalization and we can tell its a vice versa of normalisation. By doing it we can increase the performance (increasing redundancy as well)


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