src/Model.php
static function Db() : Connection {
        if (!isset(self::$_connection)) {
            [$host, $port, $user, $password, $db_name, $charset] = self::$_config;
            self::$_connection = new Connection($host, $port, $user, $password, $db_name, $charset);
        }
        return self::$_connection;
    }
static function Db() : Connection {
        if (!isset(self::$_connection)) {
            [$host, $port, $user, $password, $db_name, $charset] = self::$_config;
            self::$_connection = new Connection($host, $port, $user, $password, $db_name, $charset);
        }
        return self::$_connection;
    }
static function Db ( ) : Connection { if ( ! isset ( self :: $ _connection ) ) { [ $ host , $ port , $ user , $ password , $ db_name , $ charset ] = self :: $ _config ; self :: $ _connection = new Connection ( $ host , $ port , $ user , $ password , $ db_name , $ charset ) ; } return self :: $ _connection ; }
获取当前实例的数据库连接

@return Connection
获取当前实例的数据库连接