1 / 17

NORMALIZATION

NORMALIZATION. Chapter objective:. What is Normalization Need of Nomalization Procees of Normalization Types of Normalization. Definition:.

lyndon
Download Presentation

NORMALIZATION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NORMALIZATION Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  2. Chapter objective: • What is Normalization • Need of Nomalization • Procees of Normalization • Types of Normalization Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  3. Definition: • Normalization is the process of organizing the fields and tables of a relational database to minimize redundancy and dependency. • Usually involves dividing large tables into smaller (and less redundant) tables and defining relationships between them. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  4. Need of Normalization • Relations that have redundant data may have problems called update anomalies, which are classified as , • Insertion anomalies • Deletion anomalies • Modification anomalies Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  5. First Normal Form Tables are said to be in first normal form when: • The table has a primary key. • No single attribute (column) has multiple values. • The non-key attributes (columns) depend on the primary key. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  6. Unnormalised form: In below table there is a violation of first normal form as a single field has been allowed to contain multiple values. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  7. A design that complies with 1NF first normal form makes use of two tables: a Customer Name table and a Customer Telephone Number table. Customer name table Customer telephone number table Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  8. Result: • Repeating groups of telephone numbers do not occur in this design • With Customer ID as key fields, a "parent-child" or one-to-many relationship exists between the two tables Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  9. Second Normal Form • A relation is in second normal form if it is in 1NF. • And every non key attribute is fully functionally dependent on the primary key. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  10. For example… A table that violates Second Normal Form Primary key Here the primary key is a composite key on emp_num and dept_no. But the value of dept_name depends only on dept_no, not on the entire primary key. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  11. Correcting Second Normal Form violations by creating two tables Emp_dept(emp_num,dept_no) dept (dept_no,dept_name) Primary key Primay key Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  12. Third Normal Form: For a table to be in Third Normal Form, • A table is in second normal form (2NF) • a non-key field cannot depend on another non-key field. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  13. A table that violates Third Normal Form Dept(dept_no,dept_name,mgr_emp_num,mgr_lname) Depend on non key Primary key Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  14. Solution: • split the Dept table into two tables: Dept table Primay key Employee table Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  15. Benefits of Normalization • Greater overall database organization. • Reduction of redundant data. • It is much easier to modify a small table with little data than to modify one big table • Consistent and accurate data within a database. VineetRaoKohite (Dept. of computer ,Govt college aron)

  16. Any Query ???? Vineet Rao Kohite (Dept. of computer ,Govt college aron)

  17. Thankyou………. Vineet Rao Kohite (Dept. of computer ,Govt college aron)

More Related