How is verification code verified?

Got a simple verification code at the beginning of only a verification code of the input box and the verification code picture submitted can be printed after you enter the verification code is correct or wrong later I added a text box added a few words SQL statement want to do a simple validation commit but do not know how to verify In practice, it's definitely not just a hint of error or correct. What if the error should prevent the form from being submitted? Another problem that needs to be solved first is that the CAPTCHA itself does not need to be inserted into the database, but there is a name in the form of the CAPTCHA. If the SQL statement is not processed, click Submit will be an error. Invalid parameter number:number of bound variables does not match number of tokens in d:wampwwwyzm1.php on line 28

    
  
       
  
   prepare("insert into test(num)values(:num)");        $stmt->execute($_POST);    }    ?>

Reply content:

Got a simple verification code at the beginning of only a verification code of the input box and the verification code picture submitted can be printed after you enter the verification code is correct or wrong later I added a text box added a few words SQL statement want to do a simple validation commit but do not know how to verify In practice, it's definitely not just a hint of error or correct. What if the error should prevent the form from being submitted? Another problem that needs to be solved first is that the CAPTCHA itself does not need to be inserted into the database, but there is a name in the form of the CAPTCHA. If the SQL statement is not processed, click Submit will be an error. Invalid parameter number:number of bound variables does not match number of tokens in d:wampwwwyzm1.php on line 28

    
  
       
  
   prepare("insert into test(num)values(:num)");        $stmt->execute($_POST);    }    ?>

  
   prepare("insert into test(num)values(:num)");                $stmt->execute(array(':num'=>$_POST['num']);            }else{                echo "wrong";          }        }    }?>

You can write this

