Forms and Databases in PHP

webdev@rgu
forms and databases in php

PROGRAM INPUTPHP CAN RECEIVE INPUT FROM A NUMBER OF
DIFFERENT SOURCES, EACH HANDLED DIFFERENTLY
• FROM HTTP REQUESTS
• KEY/VALUE PAIRS EMBEDDED IN GET
REQUESTS
• DATA INCLUDED IN THE BODY OF A POST
REQUEST
• FROM RESOURCES
• CONNECTING TO A DATABASE TO RETRIEVE
INFORMATION

USING ‘GET’
THE GET KEYWORD ALLOWS US TO RETRIEVE DATA
THAT IS STORED IN THE ADDRESS OF THE WEB PAGE
WWW.MYSITE.COM/RANDOMPAGE.PHP
WWW.MYSITE.COM/RANDOMPAGE.PHP?USERNAME=MIKE

sending variables
RANDOMPAGE.PHP?USERNAME=MIKE&GENDER=MALE
TO USE MORE THAN 1 KEY/VALUE PAIR SEPARATE
THEM WITH AN AMPERSAND

START WITH A QUESTION MARK
sending variables

START WITH A QUESTION MARK
VARIABLENAME=VALUE
sending variables

<A HREF=“MYPAGE.PHP?USERNAME=MIKE>CLICK ME</A>
WE CAN USE THIS TO PASS INFORMATION
BETWEEN PAGES
$LOCATION = “MYPAGE.PHP?USERNAME=MIKE”;
HEADER($LOCATION);
IN HTML
IN PHP
THERE WILL BE OTHER WAYS THAT YOU’LL FIND
TO USE THIS AS WELL
sending variables

TAKE THE VARIABLE FROM GET AND ASSIGN IT TO
A STANDARD VARIABLE. YOU CAN THEN USE IT IN
YOUR CODE
using variables

JUST A REMINDER, YOU CAN MAKE YOUR ECHO
STATEMENTS MORE COMPLICATED
CURLY BRACKETS MAKE YOUR LIFE A LOT EASIER,
IT MAY BE WORTH GIVING THEM A GO!
combining in statements

using information from html forms
A SECOND INPUT FOR PHP SCRIPTS IS BY USING
FORMS
• HTML FORMS CAPTURE USER INPUT
• FORM ELEMENTS HAVE NAMES AND WHEN THE
FORM IS SUBMITTED A VALUE IS SET TO THE
CURRENT NAME
• FORM INFORMATION IS ADDED TO
• THE BODY OF THE HTTP REQUEST IF THE FORM
METHOD IS POST
• THE PARAMETERS OF THE HTTP REQUEST IF THE
FORM METHOD IS GET

simpleform.html
HTML FILE CONTAINING A FORM

submitform.php
PHP FILE READING THE FORM INFORMATION

using get in forms
WE CAN ALSO USE THE GET METHOD IN THIS
EXAMPLE BUT WE WOULD NEED TO ALTER
SIMPLEFORM.HTML AND SUBMITFORM.PHP IN
ORDER TO DO THIS
• THERE ARE LIMITATIONS TO HOW MUCH
INFORMATION CAN BE ENCODED IN A URL STRING
• THIS IS BROWSER SPECIFIC
• SECURITY CONCERNS ALSO EXIST BECAUSE THE
HTTP HEADER IS EXPOSE AND CAN BE INSPECTED
BY THIRD PARTIES
• USING POST MAKES THIS EASIER TO PROTECT

linking your form to a
database

using a database
ONE OF THE MOST COMMON TASKS THAT YOU
WILL WANT TO DO WITH A WEB FORM IS STORE
THE INFORMATION IN A DATABASE
• COVERED THIS LAST WEEK BUT IT IS WORTH
GOING OVER AGAIN

simpleform.html
WE WILL USE THE SAME FORM AS BEFORE

submitform.php
• CONNECT TO THE DATABASE

submitform.php
• OBTAIN THE $POST VARIABLES

submitform.php
• FORM THE SQL QUERY

submitform.php
• RUN THE SQL QUERY

submitform.php
• RUN THE SQL QUERY
• REDIRECT TO ANOTHER PAGE

viewusers.php
CONNECT TO THE DATABASE

PUT IN THE HTML HEADERS
viewusers.php

START AN UNORDERED LIST
viewusers.php

OPEN UP THE PHP TAGS
viewusers.php

WRITE THE SQL QUERY
viewusers.php

WRITE THE SQL QUERY
RUN THE QUERY
viewusers.php

WRITE THE SQL QUERY
RUN THE QUERY
USE THE WHILE LOOP TO OF THROUGH IT
viewusers.php

WRITE THE SQL QUERY
RUN THE QUERY
• FOR ROW THAT EXISTS
viewusers.php

WRITE THE SQL QUERY
RUN THE QUERY
• TURN THE $ROW VARIABLES INTO NORMAL VARIABLES
viewusers.php

WRITE THE SQL QUERY
RUN THE QUERY
• TURN THE $ROW VARIABLES INTO NORMAL VARIABLES
• ECHO THEM OUT
viewusers.php

Forms and Databases in PHP

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