Gravity Forms modify lead detail table

gf-ldtable.php

<?php 

function update() {
	
	global $wpdb;

	// get the lead detail table name
	$lead_details_table_name = RGFormsModel::get_lead_details_table_name();

	// as stored in the $lead_details_table_name * 10
	// these are respective to the form field ids for a constructed form
	$field_number_old_values = array(
		50, // email
		70, // username
			// etc.
	);

	// field values taken from the new entry
	$field_number_new_values = array(
		'a',
		'b',
			// $entry['5'], // email
			// $entry['6'], // username
			// etc.
	);

	$size = count( $field_number_new_values );

	$when = '';
	$in = '';

	// get current user name, has to have a respective entry in the 6th field of Membership form
	$user = wp_get_current_user();
	$username = $user->display_name;

	// select lead id for the currently logged in user
	$query = "SELECT lead_id FROM $lead_details_table_name WHERE value = %s";
	$prepare = $wpdb->prepare( $query, $username );

	// get lead ID for the given username
	$lead_id = $wpdb->get_var( $prepare );
	var_dump( $lead_id );

	// construct when part of the sql update statement
	// construct the 'IN' part of the SQL query to make sure that other fields don't get affected
	// http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html#operator_case
	for ( $i = 0; $i < $size; $i++ ) {
		$when .= "WHEN {$field_number_old_values[$i]} THEN '{$field_number_new_values[$i]}' ";
	
	}
	$in = implode( ', ', $field_number_old_values );
	
	// use ROUND to omit floating point error http://dev.mysql.com/doc/refman/5.0/en/problems-with-float.html
	$query = "UPDATE $lead_details_table_name
    SET value = CASE ROUND(field_number*10) 
        $when
    END
    WHERE ROUND(field_number*10) IN ($in) AND lead_id = $lead_id";

	$query = $wpdb->query( $query );
}