SQL Introduction
In this chapter of Oracle SQL Tutorial, we will get the overview of Oracle SQL and will know about its usages.
SQL stands for Structured Query Language.
SQL is a declarative language and is what is being used when statements such as SELECT, INSERT, UPDATE and DELETE are entered in a tool that communicates with the database.
RDBMS – Relational Database Management System
A database is an organized collection of information. A table is the basic unit of storage structure for most databases. It is made up of columns and rows that store data:
| Column 1 | Column 2 | Column 3 | Column4 | |
| Row 1 | data | data | data | data |
| Row 2 | data | data | data | data |
| Row 3 | data | data | data | data |
| Row 4 | data | data | data | data |
| Row 5 | data | data | data | data |
To manage databases, you need a database management system (DBMS). A DBMS is a program that stores, retrieves, and modifies data in the database on request. A relational database management system (RDBMS) uses relations, or two-dimensional tables to store information.
Properties of relational database management systems include:
1. Ability to be accessed and modified by executing SQL statements
2. Contain collection of tables with no physical pointers
3. Uses a set of operators
SQL statements are usually entered through software that has the ability to communicate with the RDBMS. The statement is sent to the database and the data is displayed through the software