(i) XAMPP is a free and open source package.
(ii) It was developed by Apache.
(iii) It is a software platform for MySQL, PHP and Peri programming languages.

In relational database model,
(i) Table is defined as the collection of data organized in terms of rows and columns.
(ii) Table is the simple representation of relations. The true relations cannot have duplicate rows

(i) Indexed method
(ii) Random Method
(iii) Sequential Method

(i) A set of stored queries is known as view in SQL.
(ii) A View contains rows and columns just like a real table.

Single Valued Attribute: A single valued attribute contains only one value for the attribute and they don't have multiple numbers of values.
Multi Valued Attribute: A multi valued attribute has more than one value for that particular attribute.

(i)  A single entry in a table is called a Row or Record or Tuple.
(ii) Set of related data are represented in a row or tuple.
(iii) The horizontal entity in a table is known as a Record or row.

The three major parts that forms a database are Tables, Queries and Views.
(i) Tables - similar to an excel sheet, containing multiple rows and columns. Where each row is a record and each column is an attribute.
(ii) Queries - It is a question with multiple conditions posted to the database. The records in the database that satisfies the passed conditions are retrieved.
(iii) Views - A set of stored queries.

(i) DB2
(ii) MySQL
(iii) Oracle
(iv) PostgreSQL
(v) SQLite
(vi) SQL Server
(vii) Sybase

(i) USE Database: This command is used to select the database in MySQL for working.
Syntax:
mysql>use test:
Database changed
mysql>
(ii) SHOW Database: Lists all the databases available in the database server.
Syntax:
mysql>show databases;
(iii) SHOW Tables: Lists all the tables available in the current database we are working in.
Syntax: mysql>show tables;

List of privileges available in MySQL

1. Primary Key:
(i) This key of relational table identifies each record in the table in a unique way.
(ii) A primary key which is a combination of more than one attribute is called a composite primary key.
(iii) The candidate key that is chosen to perform the identification task is called the primary key
2. Foreign Key:
(i) A foreign key is a "copy" of a primary keythat has been exported from one relation into another to represent the existence of a relationship between them
(ii) A foreign key is a copy of the whole of its parent primary key i.e if the primary key is composite, then so is the foreign key.
(iii) Foreign key values do not (usually) have to be unique.
(iv) Foreign keys can also be null.
(v) A composite foreign key cannot have some attribute(s) null and others non-null.
3. Candidate Key:
(i) Each super key is called a candidate key.
(ii) A candidate key is selected from the set of Super Key.
(iii) While selecting candidate key, redundant attributes should not be taken.
(iv) The candidate key is also known as minimal super keys.
4. Super Key:
(i) An attribute or group of attributes, which is sufficient to distinguish every tuple in the relation from every other one is known as Super Key.
5. Composite Key (Compound Key):
(i) A key with more than one attribute to identify rows uniquely in a table is called Composite key.
(ii) This is also known as Compound Key.

SQL - Structured Query Language is a stand. language used for accessing and manipulating databases.
Data Definition Language (DDL)
The DDL commands are used to define database schema (Structure). Also to create and modify the structure of the database object in the database. CREATE, ALTER, DROP,RENAME and TRUNCATE commands belongs to this category.
SOL DDL COMMANDS LIST

Create Database used to create new SQL Database.
Syntax: CREATE database databasename;
Example: mysql>create database studentDB;
Drop Database - used to remove any of the existing SQL Database.
Syntax: DROP database databasename;
Example: mysql>DROP database studentDB;
TRUNCATE Command:
Syntax: TRUNCATE table tablename;
Example: TRUNCATE table studentDB;
ALTER Command:
Syntax:
ALTER TABLE table_name
ADD column_name column_definition;
Example:
ALTER TABLE student
ADD student_name char(50);

ER Modeling basic concepts: The basic concepts of ER model consists of
1. Entity or Entity type
2. Attributes
3. Relationship
(i) Entity (or) Entity type
(i) An Entity can be real-world object (or) animation which is easily identifiable by anyone even by a common man.
(ii) Example: In a company's database Employee, HR, Manager are considered as entities, where each of these entity will be having their own attributes.An entity is represented by a rectangular box.

Types of Entity:
(a) Strong Entity
(b) Weak Entity
(c) Entity Instance
(i) Strong Entity
1. Strong entity is not depend on other entity and it will have a primary key.
2. It is represented by one rectangle.

3. For Example Roll Number. Everyone Roll Number varies and it will not be same.
(ii) Weak Entity
1. A weak entity is dependent on other entities and it doesn't have any primary key like strong entity.
2. It is represented by double rectangle.

3. For Example, "Marks" is the weak entity and there is no primary key or unique id. It is depend on the existence of the other entity.

(iii) Entity Instance
1. Instances are the values for the entity. So an Entity Instance denotes the category values for the given entity.
Entities Instances

2. Attributes
An attribute is the information about that entity and it will entity describe, quantity, qualify, classify and specify and entity. An attribute will always have a single value, that value can be a number or character or string.
Types of attributes :
(i) Key Attribute
(ii) Simple Attributes
(ii) Composite Attributes
(iv) Single Valued Attribute
(v) Multi Valued Attribute
3. Relationship Type
In ER Model, relationship exists between two entities. Three types of relationships are available and the Entity-Relationship (ER) diagram is based on the three types listed below
(i) One-to-One relationship: Consider two entities A and B. One-to-one (1:1) relationship is said to exist in a relational database design, if 0 or 1 instance of entity A is associated with 0 or 1 instance of entity B, and 0 or 1 instance of entity B is associated with 0 or I instance of entity A.
(ii) One-to-Many relationship: Consider two entities A and B. One-to-many (1:N) relationship is said to exist in a relational database design, for 1 instance of entity A there exists 0 or 1 or many instances of entity B, but for 1 instance of entity B there exists 0 ur 1 instance of entity A.
(iii) Many-to-Many relationship: Consider two entities A and B. many-to-many (M:N) relationship is said to exist in a relational database design, for 1 instance of entity A there exists 0 or 1 or many instances of entity B, and for 1 instance of entity B there exists 0 or 1 or many instance of entity A.
In reality one-to-one are in less usage, where as one-to-many and many-to-many are commonly used. However in relational database, many-to-many are converted into one-to-many relationships.