PHP sql query WHERE value = 0-CodePudding

I am making a WordPress plugin. I have to create a Name and email checker. I have a form with POST method. In this form you fill your email and name

<form method="post">
    <input type="text" name="yourname" placeholder="name" required>
    <input type="text" name="mail" placeholder="email" required>
    <input  type="submit" value="Add">
</form>

Then i want to make a sql query to check if there is a user with the email that has been filled in. I did console.log $EmailCheckResults` from below here. and it gives this back:

SELECT user_email FROM users WHERE user_email = 0

Code:

global $wpdb;
        
$emailToCheck = $_POST['mail'];     
$EmailCheckResults = $wpdb->prepare("SELECT user_email FROM users WHERE user_email = %d", $emailToCheck);
$CheckResults = $wpdb->get_var($EmailCheckResults);

any ideas why %d is 0? even if i fill in the email input?

CodePudding user response：

An email-id is always a string, so use %s instead of %d

%s represents a string.

%d represents digits.

So the code needs to be:

$EmailCheckResults = $wpdb->prepare("SELECT user_email FROM users WHERE user_email = %s", $emailToCheck);

CodePudding user response：

In WordPress, there is a function called email_exists( $email ) which you can use for checking if the email is already used by another user or not. If the email is already used, then the existing user_id is returned.

Check this function: https://developer.wordpress.org/reference/functions/email_exists/

Hope this will also help.

CodePudding user response：

According documentation %d mean - digit placeholder. Use %s for strings.