MySQL Introduction

MySQL is a relational Database Management System. In the Relational database Model, all the information is stored on Tables, these tables are divided into rows and columns.

A collection of related tables are called DATABASE. A named table in a database is called RELATION in Relational Data Model. The row in a table is called TUPLES, and the column of a Table is called ATTRIBUTE. No. of rows in a table is called DEGREE of the table and no. of columns in a table called CARDINALITY.

These are few terms that every computer science student must be aware of if he/she is going to learn Database/SQL.

Primary Key: An attribute or a group of the attribute which can distinguish a row uniquely in a table is Called Primary key/Key Field/Key attribute.

Candidate key: The attributes which are capable to act as a primary key are known as a candidate key.

Alternate key: An attribute that can act as a primary key in place of the primary key is called an alternate key.

Foreign Key: An attribute in its present table whose values are derived from some other table, is called a foreign key in the present table.

SQL stands for a structured query language, a language to manipulate the database. Nowadays It is a universal database language to create, manipulate databases across plate forms. The whole SQL is divided into three major parts

  1. DDL  (Data Definition Language)
  2. DML(Data Manipulation Language)
  3. TCL ( Transaction Control Language)

DDL( Data Definition Language ):

The commands that is covered under this category is used to define and manipulate the structure of the database and its associated tables. Create Table, Alter Table and Drop Table are its major commands.

DML ( Data Manipulation Language ):

DML stands for data manipulation language. This is basically responsible for managing the records( row/tuple) of any table. The main command falls under this category are INSERT, DELETE, UPDATE, SELECT and CREATE VIEW, DROP VIEW

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