Driver_Database_Driver_MySQL::connect

连接数据库

$use_connection_type 默认不传为自动判断，可传true/false,若传字符串(只支持a-z0-9的字符串)，则可以切换到另外一个连接，比如传other,则可以连接到$this->_connection_other_id所对应的ID的连接

null Driver_Database_Driver_MySQL::connect( [ boolean $use_connection_type = null ] )

参数列表

参数类型描述默认值

$use_connection_type boolean 是否使用主数据库 null

参数	类型	描述	默认值
`$use_connection_type`	`boolean`	是否使用主数据库	null

File: ./drivers/database/mysql/mysql.class.php

public function connect($use_connection_type = null)
{
    if (null!==$use_connection_type)
    {
        $this->_set_connection_type($use_connection_type);
    }

    $connection_id = $this->connection_id();

    # 最后检查连接时间
    static $last_check_connect_time = 0;

    if (!$connection_id || !isset(Database_Driver_MySQL::$_connection_instance[$connection_id]))
    {
        $this->_connect();
    }

    # 如果有当前连接，检查连接
    if ($last_check_connect_time>0 && time()-$last_check_connect_time>=5)
    {
        # 5秒后检查一次连接状态
        $this->_check_connect();
    }

    # 设置编码
    $this->set_charset($this->config['charset']);

    # 切换表
    $this->_select_db($this->config['connection']['database']);

    $last_check_connect_time = time();
}