core/DB.php
public static function existsField(string $tbname, string $field)
    {
        return self::engine()->existsField($tbname, $field);
    }
public static function existsField(string $tbname, string $field)
    {
        return self::engine()->existsField($tbname, $field);
    }
判断字段是否存在
@param string $tbname
@param string $field
@return bool
@throws MysqlException