1. MySQL and PHP
By Trevor Adams

2. Topics Covered What is SQL? SQL Standards MySQL MySQL and PHP Database
Tables
Queries
Data Manipulation Language (DML)
Data Definition Language (DDL)
MySQL and PHP
Connecting to MySQL Server
Using a connection
Functions

3. What is SQL? Structured Query Language Allows database operations
Retrieve data
Modify data
Insert new data
Remove data
Create and modify tables
English type syntax

4. SQL Standards ANSI (American National Standards Institute)
SQL is available on many platforms and products
Many products implement specific features that are exclusive
A product must meet the requirements of ANSI SQL to be considered ANSI SQL compliant
Assists programmers by using a common syntax

5. MySQL Available as both a commercial and open-source product
Implements the SQL standards
Available on many platforms
Windows
Linux
Mac
Unix
Available from

6. MySQL - Database A MySQL server is capable of storing many databases
A database is generally made of a collection of related tables
Each student will get one database for use with the module
Every database will be accessible by the student that owns it

7. MySQL - Tables A database is generally made up of related tables
Each table will have a name that is unique within the database
A table contains records with data
StudentID
Forename
Surname
Level
AK123900
Trevor
Adams M
AB340948
Bobby
Ratchet 3
AC234887
Johan
Doex 2

8. MySQL - Queries StudentID AK123900 AB340948 AC234887
A query performed on a database can result in data or some kind of status
A returned list of required records
Whether a deletion was successful
SELECT StudentID FROM Student
Returns a result set
StudentID
AK123900
AB340948
AC234887

9. MySQL - Queries Queries can come in the following forms:
SELECT – extracting data
UPDATE – updates data
DELETE – deletes data
INSERT – inserts data
All of these queries can be used on the MySQL database software

10. Data Manipulation Language
Consists of the queries that enable the developer to modify the data contained
The SQL server processes these queries and returns a result set or a status notification

11. Data Definition Language
Defines a set of queries that can be used by the developer to modify the data structure
CREATE TABLE
ALTER TABLE
DROP TABLE
CREATE INDEX
DROP INDEX
We shall not be covering these commands to a great extent
Use a management tool to generate these commands automatically

12. PHP and MySQL
PHP contains all of the functionality required to interact with MySQL servers
Most PHP MySQL functions are prefixed with ‘mysql_’
Use the PHP homepage to search for mysql_ and examine the results
MySQL is a client-server based DBMS
Database management system
One (or few) server(s) caters for many clients
Possible for web server and DBMS server to be on the same system

13. Connecting to MySQL with PHP
Use the MySQL connect routine
mysql_connect($host, $user, $password)
$user and $password will be your account details
mysql_connect will return a link ID
$link = mysql_connect($host, $user, $password)
if(!$link) { echo “Unable to connect”; }
Always check the link to ensure that the database connection was successful

14. Selecting a database
Once a link has been established, select a database
mysql_select_db($dbname, [$link])
[] optional – uses last created $link if not given
mysql_select_db returns a Boolean indicating status
$result = mysql_select_db(“students”)
If(!$result) { echo “No database”; }

15. Using a Connection
Once a connection has been established it is possible to execute queries
Queries always return a result
Success status
Result Set
Use mysql_query($query_string) to execute
$query = “SELECT * FROM Students”;
$result = mysql_query($query);
$result will contain the desired result set or false if not available

16. Using a Connection
Use functions mysql_fetch_row($result) to obtain a row from the result set
Returns false when no rows left
Example:
$query = “SELECT * FROM Students”;
$result = mysql_query($query);
While($row = mysql_fetch_row($result)){
// $row will be an array index at 0 per column }
$row will be equal to false (ending the while loop) when there are no more rows left

17. SQL Query Types
SELECT
SELECT [fields,…] FROM [table] WHERE [criteria] ORDER BY [field] [asc,desc]
[fields] can be * for all or field names separated by commas
[table] is the name of the table to use
[criteria] is a collection of Boolean expressions that limits returned rows E.g.
Forename=‘Trevor’ AND Surname=‘Adams’
[field] denotes which field to sort by

18. SQL Query Types INSERT INTO
INSERT INTO [table]([fields,…] VALUES([newvalues,…])
[table] indicates which table to insert into
[fields] is a comma separated list of fields that are being used
[newvalues] is comma separated list of values that directly correspond to the [fields]
E.g. INSERT INTO students(StudentID, Surname, Forename, Level) VALUES(‘AK301390’, Adams, Trevor, M)

19. SQL Query Types UPDATE [table] denotes the table to update
UPDATE [table] SET [field=value,…] WHERE [criteria]
[table] denotes the table to update
[field=value,…] is a comma separated list of values for fields
[criteria] – a Boolean expression that specifies which records to update
If no criteria is given, all records would be updated
UPDATE students SET forename=‘Trevor’ WHERE StudentID=‘AK301390’
With no where clause every record in the table would be updated with forename=‘Trevor’

20. SQL Query Types DELETE Simple and dangerous statements
DELETE FROM [table] WHERE [criteria]
Simple and dangerous statements
[table] to delete from
[criteria] specifying records to delete
No criteria deletes all records
DELETE FROM students
Removes all student records with no warning and no sympathy for mistakes.
E.g. DELETE FROM students WHERE StudentID=‘AK301390’
Deletes the student with StudentID of ‘AK301390’

21. Quick Example
$query = “INSERT INTO students (StudentID, Forename, Surname, Level) VALUES (‘AK301390’, ‘Trevor’, ‘Addams’, ‘M’)
$result = mysql_query($query);
if(!$result) {
Echo “Insertion failed”;
} else {
Echo “Record inserted”; }

22. Quick Example
$query = “UPDATE students SET Surname=‘Adams’ WHERE StudentID=‘AK301390’
$result = mysql_query($query);
If(!$result) {
echo “Update failed!”;
} else {
echo “Update successful!”; }

23. Quick Example $query = “SELECT * FROM student”;
$result = mysql_query($query);
If(!$result) {
echo “No result set”;
} else {
while ($row = mysql_fetch_row($result)){
foreach($row as $value){
echo “$value, ”; }

24. Useful functions
Many mysql functions can take a link identifier but do not need it.
Simply uses the last one opened
mysql_affected_rows ( [link_identifier] )
Returns the number of rows affected from the last query
mysql_errno ( [link_identifier] )
Gets the last error number from the server
mysql_error ( [link_identifier] )
Returns a string containing error information
mysql_fetch_array (result [,result_type] )
Retrieves a record from a result set as an array, optional result time can be MYSQL_ASSOC, MYSQL_NUM or default MYSQL_BOTH.

25. Other Resources
SQL is a big topic, a walk-through tutorial will be available in the lab session
Meanwhile – take a look at the following resources:
You can obtain MySQL free of charge from
Version 5.x has just been released
University currently uses 4.x