SQL Introduction for Beginners

SQL Introduction for Beginners, What is SQL?, SQL Language Elements, SQL Syntax, SQL Database Engine, SQL Data Types, SQL Comments, SQL Operators, and SQL Functions.

SQL Introduction for Beginners, SQL – Data Definition Language, SQL – Data Manipulation Language, Data Control Language, and SQL Queries & Subqueries.

Selenium Online Training with Project (by G C Reddy)

SQL Introduction for Beginners

1. Introduction
2. Database Fundamentals
3. Subsets of SQL
4. SQL Language Elements
5. Database Development using SQL
6. Database Testing using SQL
7. SQL for Database Administration

1. Introduction:

SQL stands for Structured Query Language, and it was initially developed at IBM in the 1970s. SQL is the standard language to communicate with relational database management systems like Oracle, MS Access, MS SQL Server, MySQL, DB2, Sybase, etc.

SQL is used to create new databases, create new tables in a database, insert records in a database, update records in a database, delete records in a database, retrieve data from a Database.

SQL executes queries against a database, sets permissions on tables, procedures, and views.

SQL is used to create stored procedures in a database and it is used to create views in a database.

Database Developers use SQL to design and deploy Database table structures, forms, reports, and queries, etc.

Database Administrators (DBA) use SQL to keep databases up to date, managing database access, writing reports, documentation, and operating manuals.

Database Testers use SQL to verify data integrity, verify data manipulations (add, update, and delete), and verify data comparisons.

2. Database Fundamentals

What is Database?

A Database is a systematic collection of data, databases support storage & manipulation of data, and databases make data management easy.

Table and Record:

A Table in a Relational Database is a predefined format of rows and columns that define an entity, each column contains a different type of attribute, and each row corresponds to a single record and each Table is provided with a name.

What is DBMS?

A Database management System is a software designed to assist in maintaining and utilizing a large collection of data. The alternative to using a DBMS is to store the data in files and write application-specific code to manage it.

Using a DBMS to manage data has many advantages:

• Data Independence
• Efficient Data Access
• Data Integrity and security
• Data Administration
• Concurrent Access and Data Recovery
etc.

What is RDBMS?

RDBMS stands for Relational Database Management Systems.

All modern database management systems like SQL, MS SQL Server, IBM DB2, ORACLE, My-SQL and Microsoft Access are based on RDBMS.

Features of RDBMS:

Simple Model

Data Accuracy

Easy Access to Data

Data Integrity

Flexibility

Normalization

High Security

Feasible for Future Modifications.

3. Subsets of SQL

SQL Commands can be classified into groups based on their nature, they are,

a. Data Definition Language
b. Data Manipulation Language
c. Data Control Language

a. Data Definition Language –

Important Commands and Operations in Data Definition Language

i. Create: To create databases and database objects

ii. Alter: To modify existing database objects

iii. Drop: To drop databases and databases objects

iv. Truncate: To remove all records from a table

v. Rename: To rename database objects

b. Data Manipulation Language –

Important Commands and Operations in Data Manipulation Language

i. Select: To select specific data from a database

ii. Insert: To insert new records in a table

iii. Update: To update existing records

iv. Delete: To delete existing records from a table

c. Data Control Language –

Important Commands and Operations in Data Control Language

i. Grant: To provide access to the Database objects to the users

ii. Revoke: to remove user access rights to the database objects

iii. Deny: To deny permissions to users.

4. SQL Language Elements

Important SQL Language Elements are:

i. Identifiers:
Names of Database Objects such as Tables, Views, Columns, etc.

ii. Data Types:
Define the type of data that is contained by a Column

iii. Constants:
Symbols that represent specific data types

iv. Operators:
Perform Arithmetic, Comparison, and Logical Operations

v. Functions:
Built-in Functions to perform specific operations

vi. Clauses:
Constituent components of statements and queries.

vii. Expressions:
Produce scalar values, or tables containing columns and rows of data.

viii. Queries:
Retrieve the data based on specific criteria, this an important element of SQL.

ix. Statements Etc…

5. Database Development using SQL

Important Functions of SQL:

• Creating database objects such as tables, indexes, stored procedures, and sequences.
• Retrieving data from a database for transaction processing or analytics.
• Adding, updating, and deleting rows of data.
• Modifying database table and index structures.

6. Database Testing using SQL

We have three types of Database Testing

a. Structural Database Testing
b. Functional Database Testing
c. Non-functional Database Testing

Important Functions of SQL:

• ACID (Atomicity, Consistency, Isolation, and Durability) Properties Validation
• Ensure Data Mapping
• Ensure Data Integrity
• Business Rule Conformity
• Ensure the Accuracy of the implemented Business Rules,
Etc.

7. SQL for Database Administration

Important Functions of SQL:

• Evaluate Database features and Database related products.
• Take care of the Database design and implementation.
• Implement and maintain database security.
• Database tuning and performance monitoring.
• General technical troubleshooting.
• Database recovery.

8. SQL Rules:

SQL follows the following rules:

The structure query language is not case-sensitive. Generally, keywords of SQL are written in uppercase.
Statements of SQL are dependent on text lines. We can use a single SQL statement on one or multiple text lines.
Using the SQL statements, you can perform most of the actions in a database.
SQL depends on tuple relational calculus and relational algebra.

9. SQL – RDBMS Databases

There are many popular RDBMS available to work with.

ORACLE
It is a very large multi-user-based database management system. Oracle is a relational database management system developed by ‘Oracle Corporation’

Oracle supports all major operating systems for both clients and servers, including MSDOS, NetWare, UnixWare, OS/2, and most UNIX flavors.

MS SQL Server
MS SQL Server is a Relational Database Management System developed by Microsoft Inc. Its primary query languages are − T-SQL and ANSI SQL.

MySQL
MySQL is an open-source SQL database, which is developed by a Swedish company – MySQL AB. MySQL is pronounced as “my ess-que-ell,” in contrast with SQL, pronounced “sequel.”

MySQL is supporting many different platforms including Microsoft Windows, the major Linux distributions, UNIX, and Mac OS X.

MS ACCESS
This is one of the most popular Microsoft products. Microsoft Access is an entry-level database management software. MS Access database is not only inexpensive but also a powerful database for small-scale projects.

MS Access uses the Jet database engine, which utilizes a specific SQL language dialect (sometimes referred to as Jet SQL).