Repeating on adding data in Database - php

Question

I have a problem in my guestbook in php. After I fill up the guestbook, it works fine but when I look to my database, all the data I entered is repeated more than once.
guestbook.php
<table border="0" width="920" bgcolor="#1d1c1b" id="round"><tr><td>
<table width="400" border="0" align="center" cellpadding="3" cellspacing="0">
<tr><br>
<td><strong><h2>SEACO's Guestbook</h2> </strong></td>
</tr>
</table>
<table width="400" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<form id="form1" name="form1" method="post" action="addguestbook.php">
<td>
<table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#FFFFFF">
<tr>
<td width="117">Name</td>
<td width="14">:</td>
<td width="357"><input name="name" type="text" id="name" size="40" placeholder="Enter your name here" required/></td>
</tr>
<tr>
<td>Email</td>
<td>:</td>
<td><input name="email" type="text" id="email" size="40" placeholder="Enter your email here (Optional)"/></td>
</tr>
<tr>
<td valign="top">Comment</td>
<td valign="top">:</td>
<td><textarea name="comment" cols="40" rows="3" id="comment" placeholder="Your comment here" required></textarea></td>
</tr>
<tr>
<td> </td>
<td> </td>
<td><input type="submit" name="Submit" value="Submit" class="button"/> <input type="reset" name="Submit2" value="Reset" class="button" /></td>
</tr>
</table>
</td>
</form>
</tr>
</table>
<table width="400" border="0" align="center" cellpadding="3" cellspacing="0">
</table><br><center><strong><button class="button">View Guestbook</button> </strong></center>
<br><br></table>
addguestbook.php
<?php
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="chess"; // Database name
$tbl_name="guestbook"; // Table name
$name = $_POST['name'];
$email = $_POST['email'];
$comment = $_POST['comment'];
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect server ");
mysql_select_db("$db_name")or die("cannot select DB");
$datetime=date("y-m-d h:i:s"); //date time
$sql="INSERT into $tbl_name(name, email, comment, datetime)values('$name', '$email', '$comment', '$datetime')";
$result=mysql_query($sql);
//check if query successful
if($result){
echo "<br><br><center><font color='white' size='5'>Successful</font> <img src='images/cmark.png' width='40px'></center>";
echo "<BR>";
// link to view guestbook page
echo "<center><a href='viewguestbook.php'><button class='button'>View guestbook</button></a></center>";
echo '<br><br>';
}
else {
echo "ERROR";
}
mysql_close();
?>
viewguestbook.php
<table width="400" border="0" align="center" cellpadding="3" cellspacing="0">
<tr>
<td><strong><font color="white">View Guestbook</font> | <button class="button">Sign Guestbook</button> </strong></td>
</tr>
</table>
<br>
<?php
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="chess"; // Database name
$tbl_name="guestbook"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect server ");
mysql_select_db("$db_name")or die("cannot select DB");
$sql="SELECT * FROM $tbl_name";
$result=mysql_query($sql);
while($rows=mysql_fetch_array($result)){
?>
<table width="400" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<td><table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#FFFFFF">
<tr>
<td width="117">Name</td>
<td width="14">:</td>
<td width="357" id="input"><?php echo $rows['name']; ?></td>
</tr>
<tr>
<td>Email</td>
<td>:</td>
<td id="input"><?php echo $rows['email']; ?></td>
</tr>
<tr>
<td valign="top">Comment</td>
<td valign="top">:</td>
<td id="input"><?php echo $rows['comment']; ?></td>
</tr>
<tr>
<td valign="top">Date/Time </td>
<td valign="top">:</td>
<td id="input"><?php echo $rows['datetime']; ?></td>
</tr>
</table></td>
</tr>
</table>
<?php
}
mysql_close(); //close database
?>
</table>

Answer 1

<?php
if (!isset($_POST['name'])) {
header ("Location: guestbook.php");
exit();
}
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="chess"; // Database name
$tbl_name="guestbook"; // Table name
$name = $_POST['name'];
$email = $_POST['email'];
$comment = $_POST['comment'];
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect server ");
mysql_select_db("$db_name")or die("cannot select DB");
$datetime=date("y-m-d h:i:s"); //date time
$sql="INSERT into $tbl_name(name, email, comment, datetime)values('$name', '$email', '$comment', '$datetime')";
$result=mysql_query($sql);
unset($_POST['name']);
//check if query successful
if($result){
echo "<br><br><center><font color='white' size='5'>Successful</font> <img src='images/cmark.png' width='40px'></center>";
echo "<BR>";
// link to view guestbook page
echo "<center><a href='viewguestbook.php'><button class='button'>View guestbook</button></a></center>";
echo '<br><br>';
}
else {
echo "ERROR";
}
mysql_close();
?>

Answer 2

There is no way to execute your query 6 times until you resubmit the form by reloading or any ajax request. If your query is executed then it should return true in $result. you can use exit() inside condition to check if it works and Try to check if form submitted by submit button like this:
<?php
if(isset($_POST['Submit'])){
$host="localhost"; // Host name
$username="root"; // Mysql username
$password="root"; // Mysql password
$db_name="test"; // Database name
$tbl_name="users"; // Table name
$name = $_POST['name'];
$email = $_POST['email'];
$comment = $_POST['comment'];
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect server ");
mysql_select_db("$db_name")or die("cannot select DB");
$datetime=date("y-m-d h:i:s"); //date time
$sql="INSERT into $tbl_name(name, email, comment, datetime) values ('$name', '$email', '$comment', '$datetime')";
$result=mysql_query($sql);
//check if query successful
if($result){
echo "<br><br><center><font color='white' size='5'>Successful</font> <img src='images/cmark.png' width='40px'></center>";
echo "<BR>";
// link to view guestbook page
echo "<center><a href='viewguestbook.php'><button class='button'>View guestbook</button></a></center>";
echo '<br><br>';
exit();
}
else {
echo "ERROR";
}
mysql_close();
}
else{
echo "not set";
}