Trying to display error when required fields are not entered

[pnarendran]

Hi have a signup form with

<form action="test.php" method="post" id="insert" name="signup" onsubmit="return validateForm();"> 

and the code for test is:

<?php
require_once 'config.php';
function error($msg) {
    global $message;
    $message = $msg;
    include "signup.php";"database.php";
    die();
}
function error2($msg) {
    error("<font color=\"red\"><b><i>$msg</i></b></font>");
}
function esc($data) {
    return mysql_real_escape_string($data);
}
function getesc($varname) {
    global $$varname;
    $$varname = isset($_POST[$varname])    ? esc($_POST[$varname])    : "";
    return $$varname;
}

//Get data in local variable
getesc('CNAME');
getesc('CSTREET');
getesc('CCITY');
getesc('CZIP');
getesc('CSTATE');
getesc('CCOUNTRY');
getesc('CPHONE');
getesc('CEMAIL');
getesc('password');
getesc('securityq');
getesc('securitya');
try {    $conn = new PDO("mysql:host=$db_host1;dbname=$db_database1", $db_username1, $db_password1);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "INSERT INTO COMPANY (COMPANY_NAME, COMPANY_STREET, COMPANY_CITY, COMPANY_ZIP, COMPANY_STATE, COMPANY_COUNTRY, COMPANY_PHONE, COMPANY_EMAIL, password, securityq, securitya)
    VALUES ('$CNAME', '$CSTREET', '$CCITY', '$CZIP', '$CSTATE', '$CCOUNTRY', '$CPHONE', '$CEMAIL', '$password', '$securityq', '$securitya')";
    // use exec() because no results are returned
    $conn->exec($sql);
    echo "New record created successfully";
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
    }
$conn = null;
?> 

It works fine in inserting all values into db. I want to display msg to user when a required field like password id not entered. Can you please show me how?
Thanks

[sneakyimp]

When someone submits this form, the browser should run the Javascript function validateForm(). You would alter that function to check wither someone has failed to enter a required input. You didn't include the HTML that defines the inputs or the function so it's hard to say more.

In your PHP file, you can check the submitted data by looking at values in the superglobal variable $POST because your form has method="post" like so:

if (!isset($_POST["password"]) || empty($_POST["password"])) {
  echo "You failed to enter a password!";
}

[NogDog]

Be careful using empty() for fields that can legitimately enter a numeric value of zero, as that is also considered "empty" (along with Boolean false). If I want to make sure they entered something at all, I use this:

if(!isset($_POST['field_name']) or trim($_POST['field_name'] === '') // must use "===", not "=="

PS: empty() does an implicit isset() for you, so you don't really need both if empty() fulfills your needs.