Q:

Insert input data from HTML form into JSON object and then store it in MYSQL

I am trying to get the data from user registration form in HTML and then push the data to JSON and then get the JSON and store into MySQL. Please help me. 
HTML
    <form id="myForm" action="userInfo.php" method="post">
        <table align="center">
            <tr>
                <td><label for="FirstNameLabel" class="tableproperties">First Name</label></td>
                <td><input type="text" class="signupTextBoxStyle" name="firstName" placeholder="Enter First Name" id="FirstNameBox" required/></td>
            </tr>
            <tr>
                <td><label for="LastNameLabel" class="tableproperties">Last Name</label></td>
                <td><input type="text" name="lastName" placeholder="Enter Last Name" id="LastNameBox" class="signupTextBoxStyle" required></td>
            </tr>
        <tr>
            <td><label for="eMailLabel" class="tableproperties">Email</label></td>
            <td><input type="email" name="email" placeholder="Enter Email" id="eMailBox" class="signupTextBoxStyle" required></td>
            <td id="emailStatus"></td>
        </tr>

        <tr>
            <td><label for="passwordLabel" class="tableproperties">Password</label></td>
            <td><input type="password" name="password" placeholder="Enter Password" id="passwordTextbox" maxlength="24" class="signupTextBoxStyle" required></td>
            <td><i class="fa fa-info-circle infoIcon" title="Password must contain minimum 3 upper case, 2 lower case and 2 special chars"></i></td>
            <td><progress value="0" max="100" class="progressBar" id="progressStatus"></progress></td>
            <td id="passwordStrength"></td>
        </tr>

        <tr>
            <td><label for="confirmPasswordLabel" class="tableproperties">Confirm Password</label></td>
            <td><input type="password" name="confirmpassword" placeholder="Must be same as password" maxlength="24" id="confirmPasswordBox" class="signupTextBoxStyle" required></td>
            <td id="passwordMismatch"></td>
        </tr>

        <tr>
            <td><label for="dobLabel" class="tableproperties">D.O.B</label></td>
            <td><input type="date" name="dob" placeholder="Enter D.O.B" id="dobBox" class="signupTextBoxStyle" required></td>
        </tr>

        <tr>
            <td><label for="dobTimeLabel" class="tableproperties">D.O.B with time</label></td>
            <td><input type="datetime" name="dobTime" placeholder="Enter D.O.B with time" id="dobTimeBox" class="signupTextBoxStyle" required></td>
        </tr>

        <tr>
            <td><label for="localDOBLabel" class="tableproperties">Local D.O.B</label></td>
            <td><input type="datetime-local" name="localdob" placeholder="Enter Local D.O.B" id="localDobBox" class="signupTextBoxStyle" required></td>
        </tr>

        <tr>
            <td><label for="ssnLabel" class="tableproperties">SSN</label></td>
            <td><input type="text" name="ssn" placeholder="000-00-0000" id="ssnBox" class="signupTextBoxStyle" required pattern="^(\d{3}-\d{2}-\d{4})$"></td>
        </tr>

        <tr>
            <td><label for="usPhoneNumber" class="tableproperties" >US Phone Number</label></td>
            <td><input type="text" name="phone" placeholder="000-000-0000" id="usNumberBox" class="signupTextBoxStyle" required></td>
            <td id="phoneStatus"></td>
        </tr>

        <tr>
            <td><label for="creditLabel" class="tableproperties" id="CreditText">Credit Card Number</label></td>
            <td><input type="text" name="creditCardNumber" placeholder="Enter Credit Card Number" id="creditBox" class="signupTextBoxStyle" required pattern="^[0-9]{12}(?:[0-9]{4})?$"></td>
        </tr>

        <tr>
            <td colspan='2'>
                <input type="submit" class="btn btn-primary btn-lg btn-block signupbuttonStyle" id="sub" />
                <button type="button" class="btn btn-danger btn-lg btn-block signupbuttonStyle" onclick="location.href = 'index.html';">Cancel</button>
            </td>
        </tr>
        </table>
    </form>

PHP(Just to test  Data is getting saved to mySQL if i manually enter the data)
$json_obj = '{
      "jsonFirstName": "Kishan",
      "jsonLastName": "Kishan",
      "jsonEmail": "Kishan",
      "jsonPassword": "Kishan",
      "jsonDob": "Kishan",
      "jsonDobTime": "Kishan",
      "jsonLocaldob": "Kishan",
      "jsonSsn": "Kishan",
      "jsonPhonenumber": "Kishan",
      "jsonCreditcardnumber": "Kishan"
 }';

PHP(Error if i want to get the values from the form)
$json_obj = '{
      "jsonFirstName": (string) $_POST['firstName'],
      "jsonLastName": (string) $_POST['lastName'],
      "jsonEmail": (string) $_POST['email'],
      "jsonPassword": (string) $_POST['password'],
      "jsonDob": (string) $_POST['dob'],
      "jsonDobTime": (string) $_POST['dobTime'],
      "jsonLocaldob": (string) $_POST['localdob'],
      "jsonSsn": (string) $_POST['ssn'],
      "jsonPhonenumber": (string) $_POST['phone'],
      "jsonCreditcardnumber": (string) $_POST['creditCardNumber']
 }';

Error Description 
Parse error: syntax error, unexpected 'firstName' (T_STRING) in /Applications/XAMPP/xamppfiles/htdocs/xampp/297test/userInfo.php on line 19
REST of PHP Code
$result = json_decode($json_obj);
$firstname = $result->jsonFirstName;
$lastname = $result->jsonLastName;
$email = $result->jsonEmail;
$password = $result->jsonPassword;
$dob = $result->jsonDob;
$dobTime = $result->jsonDobTime;
$localdob = $result->jsonLocaldob;
$ssn = $result->jsonSsn;
$phonenumber = $result->jsonPhonenumber;
$creditcardnumber = $result->jsonCreditcardnumber;

if(mysql_query("INSERT INTO user VALUES('$firstname', '$lastname', '$email', '$password', '$dob', '$dobTime', '$localdob', '$ssn','$phonenumber','$creditcardnumber')")){
    echo "Successfully Inserted";
}

else
    echo "Fail to Insert";

A:

Creating JSON-Strings directly through concatenation is hard because of quotes, new line characters etc.
Instead, create an array of values and encode that into a JSON string with json_encode:
$values = array(
  "jsonFirstName" =>        $_POST['firstName'],
  "jsonLastName" =>         $_POST['lastName'],
  "jsonEmail" =>            $_POST['email'],
  "jsonPassword" =>         $_POST['password'],
  "jsonDob" =>              $_POST['dob'],
  "jsonDobTime" =>          $_POST['dobTime'],
  "jsonLocaldob" =>         $_POST['localdob'],
  "jsonSsn" =>              $_POST['ssn'],
  "jsonPhonenumber" =>      $_POST['phone'],
  "jsonCreditcardnumber" => $_POST['creditCardNumber']
);

$json_obj = json_encode($values);

Alternatively you can just do:
$json_obj = json_encode($_POST);

You will then get a JSON object with every index of $_POST. The only difference is, that you can't rename your fields as you did in your example.

