Class 2/5/2016 (Week 10)

Today class is about MySQL. We learnt about the Server Side Script which is MySQL. SQL is a standard language for accessing databases. We have learned about Database, DBMS, and also relational Databases.

What is SQL (Structured Query Language)

• SQL stands for Structured Query Language
• SQL allows you to access a database
• SQL is an ANSI standard computer language
• SQL can execute queries against a database
• SQL can retrieve data from a database
• SQL can insert new records in a database
• SQL can delete records from a database
• SQL can update records in a database
• SQL is easy to learn

Data Manipulation Language (DML)

These query and update commands together form the Data Manipulation Language (DML), 

part of SQL:

• 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

Data Definition Language  

The most important DDL statements in SQL are:

• 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 

Accessing MySQL via PHP

There are four steps process to access MySQL from a PHP script: 

Step 1: Make a connection to MySQL database server .

• require that you specify the location of the database, plus a username and password.

Step 2: Select the database within MySQL that you want to work with .

• Example: select "SIS" database.

Step 3: Issue an SQL statement/create the query.

•  could be any valid SQL keyword, example: SELECT, UPDATE.

Step 4: Iterate through the SQL result set: if you are issuing a SELECT statement, iterate through the result set and extract each record.

•  Example: extract specific fields in each record and display as HTML.