无法从给定的插入查询中插入mysql数据库中的值..它是否正确

Am trying to insert the values in the mysql database from the variables being posted from the other page and save it in the database butthe code is used to insert the values in mysql database but the query is not working it is showing errors while editing .

Parse error: syntax error, unexpected ''.$Type_of_leave.'' (T_CONSTANT_ENCAPSED_STRING) in C:\wamp\www\saveetha\staff\process_leave.php on line 53

How to make the insertion using the the query New Leave

            $con=mysqli_connect("localhost","root","","saveetha");
            // Check connection
            if (mysqli_connect_errno())
              {
              echo "Failed to connect to MySQL: " . mysqli_connect_error();
              }

            mysqli_query($con,"INSERT INTO `leave_details`(`leave_id`, `type`, `no_of_days`, `date_from`, `date_till`, `availed_leave`, `leave_reason`, `alternate_date`, `period`, `semester`, `fac_name`, `fac_desg`, `dept`, `approved_authority`) VALUES (
            NULL,
            "'.$Type_of_leave.'",
            "'.$No_of_days.'",
            "'.$from.'",
            "'.$upto.'",
            "'.$Leave_Availed.'",
            "'.$Reason_for_Leave.'",
            "'.$Alternate_leave.'",
            "'.$Period.'",
            "'.$Semester.'",
            "'.$Fac_name.'",
            "'.$Fac_desg.'",
            "'.$dept.'",
            "'.$Approved_by.'")");

             echo 'leave from updated !! ';
            mysqli_close($con);
            ?>

Your quotes are backwards:

mysqli_query($con,"INSERT INTO `leave_details`(`leave_id`, `type`, `no_of_days`, `date_from`, `date_till`, `availed_leave`, `leave_reason`, `alternate_date`, `period`, `semester`, `fac_name`, `fac_desg`, `dept`, `approved_authority`) VALUES (
        NULL,
        '".$Type_of_leave."',
        '".$No_of_days."',
        '".$from."',
        '".$upto."',
        '".$Leave_Availed."',
        '".$Reason_for_Leave."',
        '".$Alternate_leave."',
        '".$Period."',
        '".$Semester."',
        '".$Fac_name."',
        '".$Fac_desg."',
        '".$dept."',
        '".$Approved_by."')");

The problem is in quotes:

mysqli_query($con,"INSERT INTO `leave_details`(`leave_id`, `type`, `no_of_days`, `date_from`, `date_till`, `availed_leave`, `leave_reason`, `alternate_date`, `period`, `semester`, `fac_name`, `fac_desg`, `dept`, `approved_authority`) VALUES (
            NULL,
            '$Type_of_leave',
            '$No_of_days',
            '$from',
            '$upto',
            '$Leave_Availed',
            '$Reason_for_Leave',
            '$Alternate_leave',
            '$Period',
            '$Semester',
            '$Fac_name',
            '$Fac_desg',
            '$dept',
            '$Approved_by')");