SQL

Introduction

SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system, or for stream processing in a relational data stream management system. The full form of SQL is Structure Query Language.

Query

A query is a question or inquiry to a set of data. We use SQL, or Structured Query Language, to retrieve data from databases. An SQL statement needs a SELECT clause to tell it to start looking for data, a FROM clause to tell it from which table(s) to pull data, and a WHERE clause to restrict/filter the results

Basics

Query Practice #1

Query Practice #2

Query Practice #3

Query Practice #4

PL\SQL

PL/SQL is a combination of SQL along with the procedural features of programming languages. It was developed by Oracle Corporation in the early 90's to enhance the capabilities of SQL. PL/SQL is one of three key programming languages embedded in the Oracle Database, along with SQL itself and Java.

PL/SQL Practice #1

PL/SQL Practice #2

PL/SQL Practice #3

SQL Mechanisms

SQL works on 5 mechanisms -

• DRL (Data Retrieval Language)

This command is used to retrieve data form data base.

• DDL (Data Definition Language)

in this we use create, alter, droop & truncate commands.

• DML (Data Manipulation Language)

used to manipulated data existing in the database. In this we use insert, update, delete, merge, join, union.

• TCL (Transaction Control Language)

in this command we use granted and control

• DCL (Data Control Language)

in this we use commit, roll back & save point.