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SQL

Is standard lang for storing, manipulating and retrieving data in databases

Is stands for Structured Query Language

Using SQL in web site

Need

• An RDBMS database program(SQL server, MySQL …)

• To use a server-side scripting language(PHP, ASP…)

• To use SQL to get the data

• To use HTML

RDBMS

Relational Database Management System

Is the basis for SQL

The data in RDBMS is stored in database objects called tables

A table is a collection of related data entries and it consists of columns and rows

Every table is broken up into smaller entities called fields

A field is a column in a table that is designed to maintain specific information about every record in the table

A record, also called a row, is each individual entry that exists in a table

A record is a horizontal entity in a table

A column is a vertical entity in a table that contains all information associated with a specific field in a table

DataBase Table

A database most often contains one or more tables

Each table is identified by a name

Tables contain records with data

SQL Statement

Most of the actions you need to perform on a database are done with SQL statements

SQL keywords are not case sensitive

Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server

Commands

SELECT : extracts data from a database

UPDATE : updates data in a database

DELETE : deletes data from a database

INSERT INTO : inserts new data into a database

CREATE DATABASE : creates a new database

ALTER DATABASE : modifies a database

CREATE TABLE : creates a new table

ALTER TABLE : modifies a table

DROP TABLE : deletes a table

CREATE INDEX : creates an index (search key)

DROP INDEX : deletes an index