What are databases and how to create database using C ?

Answer 1

but how to code that ? I don't have little bit idea about databases.

Answer 2

For dbms usually has some library that provide a bunch of function for manipulating the database

For plain text, you can simply write a formatted text seperate each data in row or space.

Answer 3

Lets say its a place to store your data
It couls be plain text file, with certain format you're created, or an excel file, or using dbms such as mysql