php框架 - thinkPHP 这两种 配置 M 的方法,有什么区别?

<code>//第一种,在 *Model.class.php:
protected $dbName = 'ybdbshop';    //库名,也可以从配置文件,或者 D() 参数设置;
protected $tableName = 'abc';    //不加前缀的表名,也可以从类名设计;
protected $tablePrefix="";    //表前缀;
</code>

<code>//第二种:
protected $connection = array
(
    'DB_TYPE' => 'mysql',
    'DB_USER' => 'root',
    'DB_PWD'  => '',
    'DB_HOST' => 'localhost',
    'DB_PORT' => '3306',
    'DB_NAME' => 'ybdbcjd',    //库名
    'DB_CHARSET' =>    'UTF8',
);</code>

<code>//第一种,在 *Model.class.php:
protected $dbName = 'ybdbshop';    //库名,也可以从配置文件,或者 D() 参数设置;
protected $tableName = 'abc';    //不加前缀的表名,也可以从类名设计;
protected $tablePrefix="";    //表前缀;
</code>

<code>//第二种:
protected $connection = array
(
    'DB_TYPE' => 'mysql',
    'DB_USER' => 'root',
    'DB_PWD'  => '',
    'DB_HOST' => 'localhost',
    'DB_PORT' => '3306',
    'DB_NAME' => 'ybdbcjd',    //库名
    'DB_CHARSET' =>    'UTF8',
);</code>

<code class="php">class classoneModel extends Model
{
    protected $dbName = 'ybdbcjd'; 
}</code>

<code class="sql">select * from ybdbcjd.table</code>

<code class="sql">use db1
select * from db2.table</code>

<code class="sql">use db2
select * from tablez</code>