Question

Why normalization and referential integrity are important principles when designing relational databases?

Answer 1

Normalization:

Normalization is the method of organizing info to cut back redundancy and improve data integrity. social control additionally simplifies the info style in order that it achieves the best structure composed of atomic components. By normalizing info, you prepare the information into tables and columns. You make sure that every table contains solely connected information. If information isn't directly connected, you produce a brand new table for that information.

Benefits of Normalization:
There square measure several advantages of normalizing a info.

1) Minimizes information redundancy (duplicate data).
2) Minimizes null values.
3) Results in a additional compact info (due to less information redundancy/null values).
4) Minimizes/avoids information modification problems.
5) Simplifies queries.
6) The info structure is cleaner and easier to grasp.
7) You can extend the info while not essentially impacting the prevailing information.

Referential Integrity:
Referential integrity refers to the accuracy and consistency of knowledge inside a relationship. In relationships, information is joined between 2 or more tables. this is often achieved by having the foreign key reference a primary key value. Because of this, we'd like to confirm that information on each side of the link stay intact.

So denotative integrity can prevent users from:
1) Adding records to a connected table if there's no associated record within the primary table.
2) Changing values in an exceedingly primary table that lead to parentless records in an exceedingly connected table.
3) Deleting records from a primary table if there square measure matching connected records.

Design Principles for relational Data:
There area unit six main objectives that has to be consummated effectively by a decent info.
1) Usability
2) Extensibility
3) Data Integrity
4) Performance
5) Availability
6) Security
Principle 1: Each column ought to contain one worth. every column in your info ought to contain one worth. you must not have multiple values in an exceedingly single cell.

Principle 2: Every worth in an exceedingly column ought to be of an equivalent sort. among a column, each worth ought to be of an equivalent style of data. you must not combine the kind of data among a column.

Principle 3: Each record ought to be distinctive. every record in your info ought to be distinctive. you must not have over one record containing a piece of equivalent information.

Principle 4: Each piece of information ought to solely behold on in one place. each bit of information in your info ought to solely behold on in one place. you must not store an equivalent data in additional than one place.

Principle 5: The order of records in an exceedingly table shouldn't carry any that means. The order of records shouldn't be wont to indicate any that means regarding the info. If it's necessary to point the order, use a column to record it.

Principle 6: Each table ought to have a Primary Key (PK) that's distinctive for every record. every table in your info ought to have a singular column as a primary key. this could then be wont to accurately determine every record, and visit those records from another table.

Principle 7: The Primary Key (PK) shouldn't carry any that means, apart from unambiguously distinctive every record. the primary Key shouldn't carry any that means, apart from unambiguously distinctive every record.

Principle 8: Each table ought to describe one entity. Each table within the info ought to describe one logical entity. you must not combine entities among an equivalent table. each column in an exceedingly table ought to relate on to that entity.

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