Question

What is the key points of the database?​

Answer 1

Explanation:

Keys are very important part of Relational database model. They are used to establish and identify relationships between tables and also to uniquely identify any record or row of data inside a table.

A Key can be a single attribute or a group of attributes, where the combination may act as a key.

The video below covers all about the different keys in an RDBMS.

Why we need a Key?

In real world applications, number of tables required for storing the data is huge, and the different tables are related to each other as well.

Also, tables store a lot of data in them. Tables generally extends to thousands of records stored in them, unsorted and unorganised.

Now to fetch any particular record from such dataset, you will have to apply some conditions, but what if there is duplicate data present and every time you try to fetch some data by applying certain condition, you get the wrong data. How many trials before you get the right data?

To avoid all this, Keys are defined to easily identify any row of data in a table.

Let's try to understand about all the keys using a simple example.

student_id name phone age

1 Akon 9876723452 17

2. Akon 9991165674 19

3 Bkon 7898756543 18

4 Ckon 8987867898 19

5 Dkon 9990080080 17

Keys Of Database :

i. Super Key

ii. Candidate Key

iii. Primary Key

iv. Composite Key

v. Secondary or Alternative key

vi. Non-key Attributes

vii. Non-prime Attributes