I get an error of Undefined index, what is the reason?
while ($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['CandidateName'] . "</td>";
echo "<td>" . $row['Position'] . "</td>";
echo "<td><input type='radio' name='candidateid' value='".$row['candidateID']."' >";
echo "<td>" . $row['NumberofVotes'] . "</td>";
$candidateid=$row['CandidateID'];
}
Here is the error
Array ( [0] => 1 [CandidateID] => 1 [1] => Jejomar Binay [CandidateName] => Jejomar Binay [2] => President [Position] => President [3] => [NumberofVotes] => ) Array ( [0] => 2 [CandidateID] => 2 [1] => Mar Roxas [CandidateName] => Mar Roxas [2] => President [Position] => President [3] => 1 [NumberofVotes] => 1 )
I will show you now the whole code and the its working now, my output here is to add 1 in number of votes when the radio button is working. it has no error but when i selected the first radio button it only updates the second data.
<html>
<center>
<font size="2" face = "century gothic">
<?php
$con=mysqli_connect("localhost","root","","election2016");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$result = mysqli_query($con,"SELECT * FROM candidate_info");
echo "<table border='1'>
<tr>
<th>Candidate Name</th>
<th>Position</th>
<th>Vote</th>
<th>Number of Votes</th>
</tr>";
while ($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['CandidateName'] . "</td>";
echo "<td>" . $row['Position'] . "</td>";
echo "<td><input type='radio' name='candidateid' value='".$row['CandidateID']."' >";
echo "<td>" . $row['NumberofVotes'] . "</td>";
$candidateID=$row['CandidateID'];
}
echo "</table>";
mysqli_close($con);
?>
<br>
<br>
<form method = "post" action = "<?php $_PHP_SELF ?>">
<input type="text" name="candidateid" value="<?php echo $candidateID;?>">
<input name = "update" type = "submit" id = "update" value = "update">
</form>
</center>
</font>
</html>
<?php
if(isset($_POST['update'])) {
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$candidateid = $_POST['candidateid'];
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn ) {
die('Could not connect: ' . mysql_error());
}
$candidateid = $_POST['candidateid'];
$sql = "UPDATE candidate_info SET numberofvotes = 1 WHERE candidateid = '$candidateid'" ;
mysql_select_db('election2016');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not update data: ' . mysql_error());
}
echo "Updated data successfully
";
mysql_close($conn);
}
?>
The field "candidateid" should be integer data type, but you are enclosed this field value with ''(single quotes) in the update query?
$sql = "UPDATE candidate_info SET numberofvotes = 1 WHERE candidateid = '$candidateid'";
if it is an integer datatype then you should remove the single quote
$sql = "UPDATE candidate_info SET numberofvotes = 1 WHERE candidateid = $candidateid";
and in MySQL every field names are case sensitive, so as you told the field names are
candidateid, candidatename, position, numberofvotes
so, you should use these names when you retrieving the values as well
<?php
if(isset($_POST['update'])) {
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$candidateid = $_POST['candidateid'];
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn ) {
die('Could not connect: ' . mysql_error());
}
$candidateid = $_POST['candidateid'];
$sql = "UPDATE candidate_info SET numberofvotes = numberofvotes + 1 WHERE candidateid = '$candidateid'" ;
mysql_select_db('election2016');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not update data: ' . mysql_error());
}
echo "Updated data successfully
";
mysql_close($conn);
}
?>
<html>
<center>
<font size="2" face = "century gothic">
<?php
$con=mysqli_connect("localhost","root","","election2016");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$result = mysqli_query($con,"SELECT * FROM candidate_info");
?>
<form method = "post" action = "<?php $_PHP_SELF ?>">
<?php
echo "<table border='1'>
<tr>
<th>Candidate Name</th>
<th>Position</th>
<th>Vote</th>
<th>Number of Votes</th>
</tr>";
while ($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['candidatename'] . "</td>";
echo "<td>" . $row['position'] . "</td>";
echo "<td><input type='radio' name='candidateid' value='".$row['candidateid']."' >";
echo "<td>" . $row['numberofvotes'] . "</td>";
}
echo "</table>";
mysqli_close($con);
?>
<br>
<br>
<input name = "update" type = "submit" id = "update" value = "update">
</form>
</center>
</font>
</html>
there is no key in your array $row as 'candidateid' please do var_dump($row); and see what is the key name, or if these are just same as your column name in your DB table, check the name of it.
Points To Be Noted :
<form></form> for sending candidateid for updating numberofvotes.candidate_info field name is not matching with what you wrote in <table><tr></tr></table>. So, use exact column name what is there in database table.<table></table> inside <form></form>.radio button is helpful. If multiple candidate value need to be updated, then you have to use checkbox with name as array type.Updated Code:
<html>
<center>
<font size="2" face = "century gothic">
<?php
$con=mysqli_connect("localhost","root","","election2016");
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
?>
<form method="post" action = "<?php $_PHP_SELF ?>">
<?php
$result = mysqli_query($con,"SELECT * FROM candidate_info");
echo "<table border='1'>
<tr>
<th>Candidate Name</th>
<th>Position</th>
<th>Vote</th>
<th>Number of Votes</th>
</tr>";
while ($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['candidatename'] . "</td>";
echo "<td>" . $row['position'] . "</td>";
echo "<td><input type='radio' name='candidateid' value='".$row['candidateid']."' ></td>";
echo "<td>" . $row['numberofvotes'] . "</td>";
$candidateID=$row['candidateid'];
}
echo "</table>";
mysqli_close($con);
?>
<br>
<br>
<input name = "update" type = "submit" id = "update" value = "update">
</form>
</center>
</font>
</html>
<?php
if(isset($_POST['update'])) {
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$candidateid = $_POST['candidateid'];
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn ) {
die('Could not connect: ' . mysql_error());
}
$candidateid = $_POST['candidateid'];
$sql = "UPDATE candidate_info SET numberofvotes = 1 WHERE candidateid = '$candidateid'" ;
mysql_select_db('election2016');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not update data: ' . mysql_error());
}
echo "Updated data successfully
";
mysql_close($conn);
}
?>