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Relational Database Database Tables Field: Insertion Anomaly

Normalization is the process of organizing data in a database to minimize redundancy. It involves dividing tables to isolate data so that changes only need to be made in one place. The goal is to prevent anomalies like insertion, deletion, and modification anomalies that can occur when all data is in one table. Normalization follows forms like first normal form to avoid multiple values in a column and third normal form to eliminate duplicate data across tables. The benefits include more efficient, accurate databases that take up less storage space.

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98 views2 pages

Relational Database Database Tables Field: Insertion Anomaly

Normalization is the process of organizing data in a database to minimize redundancy. It involves dividing tables to isolate data so that changes only need to be made in one place. The goal is to prevent anomalies like insertion, deletion, and modification anomalies that can occur when all data is in one table. Normalization follows forms like first normal form to avoid multiple values in a column and third normal form to eliminate duplicate data across tables. The benefits include more efficient, accurate databases that take up less storage space.

Uploaded by

dinadayanithi
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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In relational database design, the process of organizing data to minimize

redundancy. Normalization usually involves dividing a database into two or


more tables and defining relationships between the tables. The objective is to
isolate data so that additions, deletions, and modifications of a fieldcan be made in
just one table and then propagated through the rest of the database via the defined
relationships.

Anomalies are problems that can occur in poorly planned, un-normalised databases
where all the data is stored in one table (a flat-file database).

Insertion Anomaly - The nature of a database may be such that it is not possible
to add a required piece of data unless another piece of unavailable data is also
added. E.g. A library database that cannot store the details of a new member until
that member has taken out a book.

Deletion Anomaly - A record of data can legitimately be deleted from a database,


and the deletion can result in the deletion of the only instance of other, required
data, E.g. Deleting a book loan from a library member can remove all details of the
particular book from the database such as the author, book title etc.

Modification Anomaly - Incorrect data may have to be changed, which could


involve many records having to be changed, leading to the possibility of some
changes being made incorrectly.

Each field in a table contains different information. For example, in an


employee list, each table would contain only one birthdate field.
Second Normal Form (2NF):Each field in a table that is not a determiner
of the contents of another field must itself be a function of the other fields in
the table.
Third Normal Form (3NF): No duplicate information is permitted. So,
for example, if two tables both require a birthdate field, the birthdate
information would be separated into a separate table, and the two other tables
would then access the birthdate information via an index field in the birthdate
table. Any change to a birthdate would automatically be reflect in all tables
that link to the birthdate table.
There are additional normalization levels, such as Boyce Codd Normal Form
(BCNF), fourth normal form (4NF)and fifth normal form (5NF). While
normalization makes databases more efficient to maintain, they can also
make them more complex because data is separated into so many different
tables.
Features
 Make the database more efficient
 Prevent the same data from being stored in more than one place (called an
“insert anomaly”)
 Prevent updates being made to some data but not others (called an “update
anomaly”)
 Prevent data not being deleted when it is supposed to be, or from data being lost
when it is not supposed to be (called a “delete anomaly”)
 Ensure the data is accurate
 Reduce the storage space that a database takes up
 Ensure the queries on a database run as fast as possible

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