Snippet - Table field install/uninstall functions

dev_script_install_uninstall_functions.php

<?php

// These 3 functions are part of a more extensive module class
private function chkField($table, $field) {
	$field = $this->db->query("DESC " . DB_PREFIX . $table . " '%" . $field . "%'");
	
	if ($field->row) {
		return true;
	}
	
	return false;
}

public function install() {
	
	if (!$this->chkField('some_existing_table', 'a_new_field')) {
		$this->db->query("ALTER TABLE some_existing_table ADD a_new_field VARCHAR(128) NOT NULL AFTER some_existing_field;");
	}		

}

public function uninstall() {
	
	if ($this->config->get('uninstall_remove_data')) {
		if ($this->chkField('some_existing_table', 'a_new_field')) {
			$this->db->query("ALTER TABLE some_existing_table DROP a_new_field;");
		}		
	}
}