why do we divide a mysql table into many smaller tables?

Question

it seems that it is a common practice to divide the data of one table into many databases, many tables to improve performance, i can understand the many datab

Answer 1

Data is split into smaller tables to 'normalize it'. This is a very interesting concept. You may read more on it here.

http://en.wikipedia.org/wiki/User:Jaseemabid/Books/Database_normalisation

A quick example.

Assume a small phonebook app, allowing people to have multiple numbers.

One way of design would be like this

• Name |Number
• A | 123
• A | 95467
• B | 179

The problem with this is that when we have to update the name of A and if we dont update all , it will cause confusion. So we can split this into two tables like this.

• Unique ID | name
• 1 | A

• 2 | B

• Unique ID | number

• 1 | 123
• 1 | 95467
• 2 | 179

This will solve the issue. constrains can be handled in an awesome manner using "foreign keys" , please read abt it to understand the whole concept properly.

Hope you get it :)