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Computer Science
MySQL Intro
Introduction to MySQL for student projects
MySQL is a widely used open source relational database management system, developed on
the client/server model. The MySQL client is an interactive command-line program that allows
you to connect to a MySQL server, run queries and view results (it can also be used in batch
mode). PhpMyAdmin is a web-based interactive client providing similar functionality in a
much more user-friendly interface.
The SQL part of MySQL refers to “Structured Query Language” which is the most common
language used to access and query databases. There is an abundance of information on the
web relating to both MySQL and SQL. As a starting point please refer to www.mysql.com
and visit the Developer Zone.
Computer Science runs a shared MySQL server on a server named csweb2.cs.qub.ac.uk. It
should be noted that this server is fire-walled by information Services and is not accessible
from outside the University campus. We provide MySQL accounts for student projects on
request. To access a MySQL account you will need a pre-assigned database name,
username and a password. Please use the Computer Science Helpdesk at
http://www.cs.qub.ac.uk/helpdesk to request accounts and provide your student number and
the name of your project supervisor.
This document is broken into three main sections.
1. Using the Web-based Interface to manage your database
A brief description of the main features of this interface is provided.
2. Using the command-line tools available on each machine in the Computer Labs
Because of the nature of the command-line tools a short set of tutorials are provided
explaining how to use these to create, query and manage your database.
3.
Connecting to a MySQL database
from other programs such as a Java application.
A brief overview of how to connect a Java application to a MySQL database with example
code is provided.
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Computer Science
1. Using
MySQL Intro
the Web-based Interface
a) Starting the MySQL phpMyAdmin interface
An intuitive web-based interface known as phpMyAdmin is available at
http://csweb2.cs.qub.ac.uk/phpmyadmin
Open this URL in any web browser and you will be presented with the login screen.
Log in with the username and password assigned to you by the system
administrator.
b) The entrance screen
This screen has a selectable list of the tables in your database in the left-hand column
and the available view and interaction options in the main column.
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Computer Science
MySQL Intro
c) Database management screen
From the Databases option you can:
o
o
o
o
o
o
o
add tables
design and modify the structure of tables and data fields
view, insert, update and delete data
search the database
prepare and execute an SQL query entered in a text field or loaded from a file
build an SQL query using the GUI tool provided
export data from your database
d) Logging out
It is important to logout when you are finished. Click on the “Home” link in the left-hand
column. Then click on the “Log out” option on the main screen.
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Computer Science
MySQL Intro
2. Using the command-line tools on the Computer Lab PCs
1. Getting Started
From the Start menu choose Programs > Accessories > Command Prompt.
You will have been given a username, a password and a database name. At the
command prompt type either of the following commands:
mysql.bat yourusername
or
mysql –h csweb2.cs.qub.ac.uk –u yourusername -p
You will be prompted for a password. Once you have the mysql> prompt you are
ready to send commands to the MySQL server to manage and display your database.
Changing your password
It is recommended that you change your password regularly for your own security. To do
this type the following:
SET PASSWORD = PASSWORD(‘newpassword’);
And press Return.
2. Connect to your database
The final step before you can type your own SQL statements is to connect to the
database. Type the following command
mysql> CONNECT databasename;
3. Displaying a table
mysql> DESCRIBE tablename
4. Running SQL commands
You can run the full range of SQL commands from the mysql prompt. This is what
simple statement would look like.
mysql> SELECT * FROM tablename;
Note: When typing long statements you can spread them over multiple lines.
MySQL determines where your statement ends by looking for the terminating
semicolon, not by looking for the end of the input line. (In other words, MySQL
accepts free-format input: it collects input lines but does not execute them until it
sees the semicolon.)
5. Running batch commands from textfiles
You can run mysql in batch mode. To do this, put the commands you want to run in a
file, then type the following :
mysql> source filename;
There are good reasons for using a script If you run a query repeatedly (say, every
day or every week), making it a script allows you to avoid retyping it each time you
execute it.
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Computer Science
MySQL Intro
3. Connecting to a MySQL database from other programs such as a
Java application
When writing applications that connect to your MySQL database you use the database
connectivity API provided by the programming environment to connect and send SQL
statements to the database server. The first step is defining the connection string.
a) Defining the connection string
Java or J2EE (JSP/Servlets)
You can use the pre-installed JDBC database drivers.
The connection string takes the form of
jdbc:mysql://csweb2.cs.qub.ac.uk/MyDatabase?user=MyUsername&password=MyPassword
Microsoft .NET, ASP.NET or ASP
You can use the preinstalled ODBC drivers.
Driver={mySQL ODBC 3.51 Driver};Server=csweb2.cs.qub.ac.uk;Port=3306;Option=4;
Database=MyDatabase;Uid=MyUsername;Pwd=MyPassword;
PHP
Pass the MySQL server address and your account details to the appropriate methods:
$mysqli = new mysqli(‘csweb2.cs.qub.ac.uk’, ‘MyUsername‘,‘MyPassword‘);
$mysqli->select_db(‘MyDatabase‘);
b) A Java database connectivity example
import java.sql.*;
public class testconn {
public static
String db =
String user
String pass
void main(String [] args) {
"yourDatabase";
= "yourUsername";
= "yourPassword";
String connStr = "jdbc:mysql://csweb2.cs.qub.ac.uk/"
connStr += db + "?user=" + user + "&password=" + pass;
System.out.println("Testing MySQL Java Connection");
try {
// register the driver
Class.forName("com.mysql.jdbc.Driver").newInstance();
System.out.println("MySQL Driver loaded successfully");
try {
// open the connection
Connection conn = DriverManager.getConnection(connStr);
System.out.println("MySQL connection opened successfully");
Statement stmt = null;
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Computer Science
MySQL Intro
ResultSet rs = null;
try {
stmt = conn.createStatement();
rs = stmt.executeQuery("SELECT * FROM person");
if (rs != null) {
System.out.println("Records were successfully retrieved");
}
else {
System.out.println("No resulting records were retrieved");
}
rs.close(); rs = null;
} catch (Exception e){
System.out.println("Could not execute query");
} finally {
stmt.close(); stmt = null;
conn.close(); conn = null;
}
} catch (SQLException ex) {
// handle any errors
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
}
} catch (Exception ex) {
System.out.println("Exception: " + ex.getMessage());
}
} // end main
}
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