SQL和PHP问题 - 错误：您的sql语法中有错误[关闭]

Error:

INSERT INTO demorequests 
         (firstname,lastname,email,phone,company,jobtitle,numberofstaff) 
VALUES 
        (Hank,Janssens,contact@hankjanssens.com,5193174848,Imaginadev,,1)

You have an error in your SQL syntax; check the manual that corresponds to your MySQL 
server version for the right syntax to use 
near '@hankjanssens.com,5193174848,Imaginadev,,1)' at line 2

Database table structure

CREATE TABLE IF NOT EXISTS `demorequests` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `firstname` varchar(30) NOT NULL,
  `lastname` varchar(30) NOT NULL,
  `email` varchar(60) NOT NULL,
  `phone` varchar(12) NOT NULL,
  `company` varchar(60) NOT NULL,
  `jobtitle` varchar(30) NOT NULL,
  `numberofstaff` varchar(12) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

PHP //assign $_POST to variables

 $firstname = $_POST['firstname'];
    $lastname = $_POST['lastname'];
    $email = $_POST['email'];
    $phone = $_POST['phone'];
    $company = $_POST['company'];
    $jobtitle = $_POST['jobtitle'];
    $numberofstaff = $_POST['numberofstaff'];

    $sql = "INSERT INTO demorequests    
    (firstname,lastname,email,phone,company,jobtitle,numberofstaff)
    VALUES ($firstname,$lastname,$email,$phone,$company,$jobtitle,$numberofstaff)";

Jonathan - When dealing with strings, VALUES need to be quoted.

('$firstname','$lastname','$email','$phone','$company','$jobtitle','$numberofstaff')

Nota: If it's an int, then quotes are not required. However, all of your columns are VARCHAR except for the id column being an AI.

Do sanitize your inputs also with mysqli_real_escape_string() since your present code is open to SQL injection.

You may always want to use stripslashes() in conjunction with mysqli_real_escape_string(), should a name contain an apostrophe.

For example: (assuming you're using mysqli_ as your connecting API).

$firstname = stripslashes($_POST['firstname']);
$firstname = mysqli_real_escape_string($con, $_POST['firstname']);

and do the same for the rest.

Or better yet:

Use mysqli with prepared statements, or PDO with prepared statements, they're much safer.

Add quotes around your string variables.

$sql = "INSERT INTO demorequests (firstname,lastname,email,phone,company,jobtitle,numberofstaff)
    VALUES ('$firstname','$lastname','$email','$phone','$company','$jobtitle','$numberofstaff')";

NOTE:

• Avoid sql injections by escaping your data, or use prepared statements.

You need to have ' around the strings in the values clause.

You need to put them in single quotes, else it won't work. This is what causing your error.

$sql = "INSERT INTO demorequests (firstname,
                                   lastname,
                                   email,
                                   phone,
                                   company,
                                   jobtitle,
                                   numberofstaff)
        VALUES ('$firstname',
                '$lastname',
                '$email',
                '$phone',
                '$company',
                '$jobtitle',
                '$numberofstaff')"

On a side note, you re vunerable for SQL attacks. Use mysqli_real_escape_string to escape all your variables.