Why do I get the MySQL Error “Query was empty”?

Question

$id = $_REQUEST[\'id\'];
$Section = $_REQUEST[\'section\'];
$Subject = $_REQUEST[\'subject\'];
$type = $_REQUEST[\'type\'];
$Start_date1 = isset($_REQUEST[\'startTxt         


        

Answer 1

You're calling mysql_query() twice, once with a non-existent $sql parameter:

mysql_query("UPDATE service SET Start_date='$Date1', Venue='$Venue', Facilitator='$Faci' WHERE ServiceID ='$id'");
if (!mysql_query($sql,$con))

should be:

if (!mysql_query("UPDATE service SET Start_date='$Date1', Venue='$Venue', Facilitator='$Faci' WHERE ServiceID ='$id'"))

You're also not escaping your input, leaving you open to SQL injection. You should use bound parameters ideally, or at the very least run your parameters through mysql_real_escape_string().

For example:

$Date1 = mysql_real_escape_string($Date1, $conn);

Answer 2

You are not setting the $sql variable and calling mysql_query() twice.

Answer 3

Please, for the love of the internet, don't built an SQL query yourself. Use PDO.