MySQL

 MySQL is database , and SQL language used access data.

What is a Database?

It is a collection of data in a format that can be easily accessed.

Why databases?

• can store large data.
• features like security, scalability etc.
• Easier to insert, update or delete data.

SQL (Structured Query Language)

SQL is a programming language used to interact with relational databases.

schema - coloum (design)

toople - rows

sql is not case sensitive;

What are Keys?

Keys are special columns in the table

Primary Key

It is a column (or set of columns) in a table that uniquely identifies each row. (a unique id)

There is only 1 PK & it should be NOT null.

Foreign Key

A foreign key is a column (or set of columns) in a table that refers to the primary key in another table.

FKs can have duplicate & null values.

There can be multiple FKs.

Note:- sql direct update nahi karne dega,error ayega,

uske liye ek line ham use karenge

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