Misc Odds and Ends

Misc Odds and Ends CSCI 297 Scripting Languages

Today • Database Normalization • Data Backups • Tracking the User with Cookies

Database Normalization • Goal= each piece of information exists only once in the database • creates storage efficiency • more efficient to update • duplicates can create inaccuracies • First Normal Form • no repeating columns with same data types • all columns contain single value • primary key uniquely identifies each row • Second Normal Form • rows do not duplicate information • Third Normal Form • data not dependent on the primary key is moved to another table

First Order two columns w/ same data type Normalization Example Second Order two rows with same info

Backing Up Data • Full Database Back Up • big pain • two possible options from the command line: • mysqldump --opt --all-database > all.sql • mysqlhotcopydatabase /path/for/backup • Full Database Restore • it's really long set of complicated steps • If concerned about data corruption • lock the table(s) • copy the records to a copy of the table(s) • unlock the table(s) • Transactions- updates can be temporary

Cookies- setting in PHP setcookie(name, value, expire, path, domain); • name • name of the cookie value • example: "usrname" • value • the value of the cookie • example = "Bob Smith" • expire • time of when the cookie expires • if empty, then the cookie expires when the browser closes • example : 24 hours from now = time()+24*60*60

Cookies- very simple example • Problem : • Script to either display the user name that is stored in a cookie or save the user name into a cookie • Possible Conditions while running the script: • a cookie was already set • isset ($_COOKIE[…]) • the cookie is being set with form data • isset ($_POST[…]) • the cookie has not been set • neither of the above is true

<?php // we have been here before and the cookie is set if (isset($_COOKIE["usrname"])) echo "Welcome " . $_COOKIE["usrname"] . "<P>"; // script is setting the cookie, expires in two minutes else if (isset($_POST['usrname'])) { setcookie ("usrname", $_POST['usrname'], time()+120); echo "Setting the cookie<P>"; } // first time visitor else { echo "Welcome first time visitor<P>"; echo "<form action='cooktest1.php' method='Post'>"; echo "User Name: <input type='text' name='usrname'><br>"; echo "<input type=submit value='Save Name'<P>"; echo "</form>"; } ?>

Cookies- common error • The setcookie() function must appear before the <html> tag. • This code is okay: else if (isset($_POST['usrname'])) { setcookie ("usrname", $_POST['usrname'], ... echo"The cookie is set.<P>"; } • This code generates an error: else if (isset($_POST['usrname'])) { echo "Setting the cookie...<P>"; setcookie ("usrname", $_POST['usrname'], ... }

Other PHP topics • Objects • Exception Handling • Authentication

Misc Odds and Ends