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Inserting Data into the Database
In this section, we'll see how we can use all the tools at our disposalto allow visitors to our site to add their own jokes to the database. If you
enjoy a challenge, you might want to try to figure this out on your own before
you read any further. There is little new material in this section. It's mostly
just a sample application of everything we've learned so far.If you want to let visitors to your site type in new jokes, you'll obviously
need a form. Here's the code for a form that will fit the bill:
<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
<p>Type your joke here:<br />
<textarea name="joketext" rows="10" cols="40" wrap>
</textarea><br />
<input type="submit" name="submitjoke" value="SUBMIT" />
</p>
</form>
As we've seen before, this form, when submitted, will load the very
same page (because we used the $_SERVER['PHP_SELF'] variable
for the form's action attribute), but with two variables
attached to the request. The first, joketext, will contain
the text of the joke as typed into the text area. The second, submitjoke,
will always contain the value "SUBMIT"; the presence of
this variable is a signal that a joke has been submitted. Both of these variables
will appear in the $_POST and $_REQUEST arrays
created by PHP.To insert the submitted joke into the database, we just use mysql_query to
run an INSERT query, using the $joketext variable
for the value to be submitted:
if (isset($_POST['submitjoke'])) {
$joketext = $_POST['joketext'];
$sql = "INSERT INTO Jokes SET
JokeText='$joketext',
JokeDate=CURDATE()";
if (@mysql_query($sql)) {
echo('<p>Your joke has been added.</p>');
} else {
echo('<p>Error adding submitted joke: ' .
mysql_error() . '</p>');
}
}The one new trick in this whole example is shown here in bold. The MySQL
function CURDATE() is used here to assign the current date as the value of the JokeDate column. MySQL actually has dozens of these
functions, but we'll only introduce them as required. For a complete function
reference, refer to "MySQL Functions".We now have the code that will allow a user to type a joke and add it
to our database. All that remains is to slot it into our existing joke viewing
page in a useful fashion. Since most users will only want to view our jokes,
we don't want to mar our page with a big, ugly form unless the user expresses
an interest in adding a new joke. For this reason, our application is well
suited for implementation as a multipurpose page. Here's the code (available
as jokes.php in the code archive):
<html>
<head>
<title> The Internet Joke Database </title>
</head>
<body>
<?php
if (isset($_GET['addjoke'])): // If the user wants to add a joke
?>
<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
<p>Type your joke here:<br />
<textarea name="joketext" rows="10" cols="40" wrap>
</textarea><br />
<input type="submit" name="submitjoke" value="SUBMIT" />
</p>
</form>
<?php
else: // Default page display
// Connect to the database server
$dbcnx = @mysql_connect('localhost', 'root', 'mypasswd');
if (!$dbcnx) {
die( '<p>Unable to connect to the ' .
'database server at this time.</p>' );
}
// Select the jokes database
if (! @mysql_select_db('jokes') ) {
die( '<p>Unable to locate the joke ' .
'database at this time.</p>' );
}
// If a joke has been submitted,
// add it to the database.
if (isset($_POST['submitjoke'])) {
$joketext = $_POST['joketext'];
$sql = "INSERT INTO Jokes SET
JokeText='$joketext',
JokeDate=CURDATE()";
if (@mysql_query($sql)) {
echo('<p>Your joke has been added.</p>');
} else {
echo('<p>Error adding submitted joke: ' .
mysql_error() . '</p>');
}
}
echo('<p> Here are all the jokes in our database: </p>');
// Request the text of all the jokes
$result = @mysql_query('SELECT JokeText FROM Jokes');
if (!$result) {
die('<p>Error performing query: ' .
mysql_error() . '</p>');
}
// Display the text of each joke in a paragraph
while ( $row = mysql_fetch_array($result) ) {
echo('<p>' . $row['JokeText'] . '</p>');
}
// When clicked, this link will load this page
// with the joke submission form displayed.
echo('<p><a href="' . $_SERVER['PHP_SELF'] .
'?addjoke=1">Add a Joke!</a></p>');
endif;
?>
</body>
</html>
There we go! With a single file that contains a little PHP code we're
able to view existing jokes in, and add new jokes to, our MySQL database.
