Oracle SQL Tutorials – Chapter 1 (Part 1 of 3)

CHAPTER 1 – INTRODUCTION TO SQL

• Explaining the capabilities of the SELECT statement
• Writing simple SELECT statements
• Select columns and aliases
• Arithmetic operators
• NULL value
• Union operator
• Usage of DISTINCT command

What is SQL ( Structured Query Language)

• It is a language that being used to manage and querying the data in relational (RDBMS) databases.
• It is not a programming language like C, C++ , Java. It is a sub-language that being used on databases like Oracle, SQL Server, Sybase, MySQL, DB2.
• SQL is a language that allows the applications and users to acces the database and make changes.

Classification of the SQL Commands

• SQL commands are classify under four parts as DDL, DML, DCL and TCL.
• DDL : Data Definiton Language
• DML : Data Manipulation Language
• DCL : Data Control Language
• TCL : Transaction Control Language

Usage Areas of SQL

• Modeling and managing the data & data models.
• Selecting, adding, deleting and updating the data.
• Creating, changing and deleting the database objects.
• Controlling the access to the database and objects.
• Providing the consistency and integrity of the database.

The Rules of Writing SQL

• SQL statements are not case-sensitive.
• SQL statements are formes in one or more lines.
• Keywords can not be shortened or divided into lines ( SELECT, FROM, DISCTINCT etc.).
• Keywords are usually placed in different lines.
• Keywords are usually writing in upper-case.
• Date and character data are alligned in left as default.
• Numerical data are alligned in right as default.

You can continue to read from this link ;

https://ittutorial.org/2019/04/02/oracle-sql-tutorials-chapter-1-2/