By default, field validations are generated as per the data type of field in database table. But you can also define extra validation on field, like max length, min length, url, equal to etc.
$pdocrud = new PDOCrud();
$pdocrud->formFields(array("user_name","email","password","confirm_password","phone"));
$pdocrud->fieldValidationType("user_name", "data-minlength", "10", "Please enter atleast 10 characters");
$pdocrud->fieldValidationType("password", "data-match", "confirm_password", "Password and confirm password not matching");
$pdocrud->formStaticFields("confirm_password", "text");
echo $pdocrud->dbTable("users")->render("insertform");