introduction

Nic Shulver, N.A.Shulver@staffs.ac.uk

Retrieving Stored DataIntroduction

This set of slides shows:The information source database structureThe data we are expecting to deal withThe output of the data reader PHP scriptThe code to build a dynamic SQL

databaseThe code to read values from a database

Retrieving Stored Data

Table: tblUsersFields:

– id, an “auto-increment” integer

– userSurname, text

– userForename, text

– userPassword, text

Note that passwords are normally stored in an encrypted form (more in later lectures)

DB Structure

Retrieving Stored DataThe PHP/SQL to create the table

// Creates the table if it isn't already there. You may prefer to build

// tables by hand using the management GUI (e.g. phpMyAdmin)

$query = 'CREATE TABLE IF NOT EXISTS tblUsers (

id INT NOT NULL AUTO_INCREMENT,

userSurname VARCHAR(30),

userForename VARCHAR(30),

userPassword VARCHAR(30),

PRIMARY KEY(id) )';

$mysqli->query($ query) or die("Could not create table: " . $mysqli->error);

Retrieving Stored DataThe data set we are using

Example dataSmall selection of

names and passwords

But no repeated surnames – not such good test data

Hard to design “realistic” data

Retrieving Stored DataSimple Search Page

The user can type ina surname,a forename,then specify the type of

searchThe interface allows for a

“wildcard” character, the asterisk sign %

% matches any text% is built into SQL% used in PHP, * used in

Access queries

Retrieving Stored DataExample Output

Read A DB Example Search Results

Running the SQL command:SELECT * FROM tblUsers WHERE userSurname LIKE 'suarez' OR userForename LIKE 'jason' ORDER BY id ASC;

492: Linda Suarez; pwd=[fr0d0ba991n5]921: Jason Imtiaz; pwd=[maskmypony]

Running the SQL command:SELECT * FROM tblUsers WHERE userSurname LIKE 's%' OR userForename LIKE 'j%' ORDER BY id ASC;

90: Luis Sanchez; pwd=[alhambra]492: Linda Suarez; pwd=[fr0d0ba991n5]921: Jason Imtiaz; pwd=[maskmypony]

Running the SQL command:SELECT * FROM tblUsers WHERE userSurname LIKE ‘%i%' AND userForename LIKE ‘%i%';

911: Toni Collins; pwd=[swissair]901: Wilbur Harris; pwd=[wilburharris]

The Code, #1<?php // ReadDB example code

// gets data from form, may be an empty stringif(isset($_REQUEST["ReadDBsearch"])){ $sUserSurname = $_REQUEST["txtUserSurname"]; $sUserForename = $_REQUEST["txtUserForename"]; $sBoolean = $_REQUEST["radioLogic"];}else // shows the REQUEST fields and server variables{ phpInfo(32); // useful when testing, NOT published site! die("We don't seem to be running the right web form...");}

Retrieving Stored DataThe Code, #2

// --------------------------------------------------- //// checks to see if all strings are empty,// if so we just go back to the search page

if( strlen($sUserSurname) + strlen($sUserForename) == 0 ){ header("Location: ReadDB.htm");}

The Code, #3

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Read A DB Example</title>

</head>

<body>

<h2>Read A DB Example Search Results</h2>

The Code, #4<?php//=====================================//// Database Section//=====================================//// Connects to a MySQL server

$id= 'xy123456';

$mysqli = new mysqli("web.fcet.staffs.ac.uk", $id, $id, $id);

$sSQL= "SELECT * FROM tblUsers WHERE userSurname LIKE '$sUserSurname' $sBoolean userForename LIKE '$sUserForename' ORDER BY id ASC;";

echo "Running the SQL command:<br /> $sSQL <br /><br />";

// searches the DB$rsMain = $mysqli->query( $sSQL );

The Code, #5//=====================================//// Outputs all the selected fields in table "tblUsers",// processes each record until we reach end of recordset

while($row = $rsMain->fetch_assoc()){ $sSurname = $row["userSurname"]; $sForename = $row["userForename"]; $sPassword = $row["userPassword"]; $nID = $row["id"];

// prints each of the fields print "$nID: $sForename $sSurname;

pwd=[$sPassword]<br />\n";}

The Code, #6//=====================================//// frees up resources$rsMain = null;$mysqli->close();?>

</body></html>

Retrieving Stored DataSearch Script Steps

So the search software takes the form data,Connects to the database,Reads only the interesting records,Holds data in a recordset,Reads the data from each of the fields,Writes information out to the user,Moves on to the next record.

Retrieving Stored DataSome notes and comments

The user interface for searching is poor – relies on knowing the “ste%en” approach to match “Steven” or “Stephen” (or “stellar alien”!)

There are serious security holes in the way the SQL is builtWhat if this script is run from a different form?The field “radioLogic” is inserted directly into the

SQL command… could contain ANY commands!More secure if we use “prepared statements”

Retrieving Stored DataConclusion

The database, script and HTML interface page are available for download

The script is only 80 lines long (so pretty short) and really needs more error trapping

The SQL, database and output are all pretty simple

But putting it all together in a working script isn’t so easy

introduction

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