Read and Write to SQL Database - php

Question

I have the script that will write info to the database, but how can I have it print the variable "time" from the database after it updated the same query based on the email entered to write to database? This is for use with JSON.
<?php
if(!empty($_POST))
{
$dbhost = 'localhost';
$dbuser = 'casaange_testapp';
$dbpass = 'testapp1';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('Could not connect: ' . mysql_error());
}
mysql_select_db('casaange_volunteertest');
$email= $_POST['email'];
$time= $_POST['time'];
$sql = "UPDATE users SET time= '$time' WHERE email = '$email'";
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
die('Could not update data: ' . mysql_error());
}
if($retval){
$response["success"] = 1;
$response["message"] = "Update successful!";
die(json_encode($response));
}
//echo '{"success":1, "message":"Time added!"}';
mysql_close($conn);
}
else
{
?>
<form method="post" action="timeinsert.php">
<table width="400" border="0" cellspacing="1" cellpadding="2">
<tr>
<td width="100">Email:</td>
<td><input name="email" type="text" id="email"></td>
</tr>
<tr>
<td width="100">Time:</td>
<td><input name="time" type="text" id="time"></td>
</tr>
<tr>
<td width="100"> </td>
<td> </td>
</tr>
<tr>
<td width="100"> </td>
<td>
<input name="update" type="submit" id="update" value="Update">
</td>
</tr>
</table>
</form>
<?php
}
?>
</body>
</html>

Answer 1

I think what you want to know is whether the UPDATE query actually changed the value in the database?
You can use mysql_affected_rows() see how many rows changed as a result of your query - in your case it will be either 1 or 0.
If you need to return the time that you just put into the database, you can query the value that actually went into the database by selecting it back out with the email address as the key.
A few general observations about your code, if I may:
You must escape that POST data before putting it into an SQL query
like that. At best it'll be a source of bugs, worst a massive
security hole.
If you're writing new code, as you appear to be here, you should
consider using the newer MySQLi or PDO_MySQL extensions instead of
the old MySQL calls.
You can use json_encode to turn an associative PHP array into a JSON
object, instead of building a JSON string yourself.