插入时出现MySQL语法错误

Question

I've got a syntax error in the following code, but I can't find it:

$tableSelect = $_POST["tableSelect"];
$companyName = $_POST["companyName"];
$telephone = $_POST["telephone"];
$fax = $_POST["fax"];
$email = $_POST["email"];
$address = $_POST["address"];
$postcode = $_POST["postcode"];
$category = $_POST["category"];
$contact = $_POST["contact"];
$contactTel = $_POST["contactTel"];
$contactEmail = $_POST["contactEmail"];
$sql = "INSERT INTO '" . $tableSelect . "' ('" . $companyName . "', '" . $telephone . "', '"
    . $fax . "', '" . $email . "', '" . $address . "','" . $postcode . "', '" . $category . "',
    '" . $contact . "', '" . $contactTel . "', '" . $contactEmail . "')";
mysqli_query($con,$sql);
if (!mysqli_query($con,$sql)) {
    die('Error: ' . mysqli_error($con));
}

Cheers!

EDIT: I have modified the code to this:

$sql = "INSERT INTO `" . $tableSelect . "` (name, telephone, fax, email, address, postcode, category,
    contact, contactTel, contactEmail) VALUES (`" . $companyName . "`, `" . $telephone . "`, `"
    . $fax . "`, `" . $email . "`, `" . $address . "`,`" . $postcode . "`, `" . $category . "`,
    `" . $contact . "`, `" . $contactTel . "`, `" . $contactEmail . "`)";

and now have the error "Error: Unknown column [companyName] in 'field list'", where [companyName] is the value submitted through the form. But surely I've defined the column as "name"?

Edit 2: Thanks, I'm now aware of the injection issue. I'd like to get it working, then I'll change it to using prepared statements.

Answer 1

Ignoring injection issues...

$sql = "
INSERT INTO $tableSelect 
(name
,telephone
,fax
,email
,address
,postcode
,category
,contact
,contactTel
,contactEmail
) VALUES 
('$companyName'
,'$telephone'
,'$fax'
,'$email'
,'$address'
,'$postcode'
,'$category'
,'$contact'
,'$contactTel'
,'$contactEmail'
);
";

Incidentally, in my (limited) experience, the practice of calling the variable (e.g. '$companyName') and the column (e.g. name) two (slightly) different things can get very confusing.