connecting php and mysql - queen's...
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Connecting PHP and MySQL
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Outline
• PHP Loops
• PHPMyAdmin
• Introducing SQL
• Connecting Database from PHP
• Exercises
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Loops
• A loop statement is a control structure that repeatedly executes a statement or a series of statements while a specific condition is TRUE or until a specific condition becomes TRUE
• Three different types of loops are:
• while statements
• do...while statements
• for statements
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While Loop
• Tests the condition prior to executing the series of statements at each iteration of the loop
• The syntax for the while statement is: while (conditional expression) {
statement(s);
}
• As long as the conditional expression evaluates to TRUE, the statement or command block that follows executes repeatedly
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While Loop • Each repetition of a looping statement is called an iteration.
• A while statement keeps repeating until its conditional expression evaluates to FALSE
• A counter is a variable that increments or decrements with each iteration of a loop statement.
• In an infinite loop, a loop statement never ends because its conditional expression is never FALSE $Count = 1;
while ($Count <= 10) {
}
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The while Structure
• PHP supports the C style while loop
– The body of the cycle will be executed until the condition is met
– The body consists of one or more statements
• If more than one, surrounding braces are required
– The condition expression is of type boolean
$a = 1;
while ($a < 100) {
$a ++;
echo $a;
}// this will output
expression
body
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2 3 4 … 99
Do .. While Loop
• Test the condition after executing a series of statements then repeats the execution as long as a given conditional expression evaluates to TRUE
• The syntax for the do...while statement is: do {
statement(s);
} while (conditional expression);
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Do .. While Cont’d
• do...while statements always execute
once, before a conditional expression is evaluated
$Count = 2;
do {
echo " <p>The count is equal to
$Count</p> ";
$Count++;
} while ($Count < 2);
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do… while Structure
• The do-while structure is similar to while-do
– The condition is checked after the body is executed!
– The body is executed at least once!
$a = 1;
do {
$a ++;
echo $a;
} while ($a < 100);
//this will produce
//the previous while cycle’s output was: 2 3 4 … 99
expression
body
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2 3 4 … 100
For Loop
• Combine the initialize, conditional evaluation, and update portions of a loop into a single statement.
• Repeat a statement or a series of statements as long as a given conditional expression evaluates to TRUE.
• If the conditional expression evaluates to TRUE, the for statement executes and continues to execute repeatedly until the conditional expression evaluates to FALSE.
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for Cycle
• PHP supports C style for cycles
– The for cycle requires initialization, iteration and
ending condition statement • None of them are obligatory • Each statement can consist of multiple comma
separated statements
for ($i = 0; $i < 10; $i++)
echo $i;
for ($i = 0, $j = 10; ; $i++, $j--)
if ($j > $i)
echo $i;
else break;
body
initialization end condition iteration
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break and continue
• You can leave a cycle with the break command
• You can move immediately to next cycle iteration with continue command
$i = 0;
while (true) {
$i ++;
if ($i == 10) break; // exit the cycle
if ($i%2 == 0) continue; // next iteration
echo $i;
}
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$i = 0;
while ($i < 10) {
if ($i%2 == 1)
echo $i;
$i ++;
}
for ($i = 1; $i < 10; $i+2)
echo $i;
will print out 1 3 5 7 9
Exercise #3
• Using PHP loops, make this HTML table.
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<td style='background-color:red'>
<td style='background-color:red'>
width = '50'
Colorful_list.php
Outline
• PHP Loops
• PHPMyAdmin
• Introducing SQL
• Connecting Database from PHP
• Exercises
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From, Tools
phpMyAdmin, we can
manage MySQL
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What is phpMyAdmin?
• PhpMyAdmin is a Web-based front end for managing mySQL databases.
• It has GUI screen for many common functions in mySQL.
• Makes mySQL more user friendly.
About phpMyAdmin
• Project started in 1998
• Uses GNU General Public License
• Platform independent
• http://www.phpmyadmin.net
What can phpMyAdmin do?
• Create and drop databases and tables.
• Work with multiple MySQL servers.
• Manage users and privileges.
• Export table data.
• Execute any SQL statement.
• 42 different languages.
• And more.
Create Database
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Create Table
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Table Specs
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Table Created
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Outline
• PHP Loops
• PHPMyAdmin
• Introducing SQL
• Connecting Database from PHP
• Exercises
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Introducing SQL (Structured Query Language)
• SQL is a data definition language (DDL)
• CREATE DATABASE `CISC492`
• CREATE TABLE ‘Students’(
Student_Number varchar(10),
First_Name varchar(20),
Last_Name varchar(20),
Email varchar(30),
Mark FLOAT)
• DROP TABLE ’Students’
• DROP DATABASE ’CISC492’
Why not INT?
Introducing SQL
• SQL is also a data manipulation language (DML)
• INSERT INTO Students
VALUES (`05771234`, `Test`, `Example`,
`[email protected]`, `89`)
• SELECT * FROM Students
WHERE `Mark` BETWEEN 85 and 95
ORDER BY `Mark` DESC
• UPDATE Students SET Email = ‘[email protected]’
WHERE Student_Number = ‘05771234’
• DELETE FROM Students
WHERE `Student_Number` = ‘05771234’
Outline
• PHP Loops
• PHPMyAdmin
• Introducing SQL
• Connecting Database from PHP
• Exercises
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Connecting Database from PHP
1) Connecting MySQL
2) Sending & Executing Query
3) Fetching Data
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1) Connecting MySQL • mysql_connect – function to connect to MySQL
server
– Returns database link identifier if successful
• mysql_select_db – function to select a particular
database from MySQL server
– Returns TRUE if successful
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$dblink = mysql_connect("local
host", "root", "rootpass");
mysql_select_db("mydb", $dblink);
Password
Database link
identifier
Server name
or IP Address Username
2) Sending & Executing Query • mysql_query ($query, $dblink) – executes query
on database.
– $query is string – the query to be executed
– $dblink is the “database link identifier” previously returned from mysql_connect
• The returned result depends on the query
– If query is select, it returns a resource (result set) on successful or false on error.
– If query is insert, update, delete, it returns true on successful or false on error.
• The link parameter $dblink can be omitted if working with only one database throughout the script.
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mysql_query("select * from students", $dblink);
3) Fetching Data
• mysql_fetch_assoc – returns associative
array containing the current row in result
and moved the pointer to the next one
– The field names are keys in the array
– Returns false if no more rows
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$result = mysql_query("select * from students")
or die(mysql_error());
while ( $row = mysql_fetch_assoc($result) )
echo "Student Number: ".$row['Student_Number'].
" Student Mark: ".$row['Mark']."<br/>";
On error, display
error message
Assignment, not
comparison,
operator
Inserting Data & Number of Rows
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$result = mysql_query (“INSERT INTO Students
VALUES (`05771234`, `Test`, `Example`,
`[email protected]`, `89`”) or die(mysql_error());
• mysql_num_rows ($result) –
returns the number of rows in a result set
$result = mysql_query ("select * from
students");
$count = mysql_num_rows($result);
echo “Total Number of Students is: $count”;
Exercise #3
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Ex1_Insert.html
Insert.php
Exercise #4
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Ex1_Insert.html
Show_Students.php
<td style='background-color:cyan'>
<th style='background-color:yellow'>
<tr style='background-color:orange'>
Descending Order
Functions (MySQL)
Category Example of functions
Aggregate MySQL: SUM, AVG, MAX, MIN, COUNT
Mathematical MySQL: SIN, COS, TAN, TRUNCATE, ROUND
Text MySQL: LEFT, RIGHT, SUBSTRING, LENGTH, LOWER, UPPER, LOCATE, REPLACE
Logical MySQL: IF, IFNULL
Conversion MySQL: FORMAT, CONVERT, DATEF_ORMAT, STR_TO_DATE
Date MySQL: CURDATE, DATEFORMAT, DAYOFMONTH, DAYOFWEEK, DAYNAME, MONTH, MONTHNAME, DATEDIFF, DATE_SUB
Time MySQL: CURTIME, HOUR, MINUTE, SECOND, TIMEDIFF
Functions (PHP)
Category Example of functions
Aggregate
Mathematical PHP: Sin, Cos, Tan, Floor, Round
Text PHP: SubStr, StrLen, StrToUpper, StrToLower, StrPos, SubStr_Replace
Logical PHP: If, While, For, Foreach, Switch
Conversion PHP: StrToTime
Date PHP: GetDate, Date
Time PHP: GetTimeOfDay, StrFTime
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