在 codeigniter 中切换数据库服务器以进行读写操作。

Question

我已经为我的数据库服务器完成了主从设置，所以在我的 codigniter 应用程序中，我想要的是在主服务器上执行所有写入选项并在从服务器上执行所有读取操作。

谁能告诉我如何在 codigniter version3 中实现这一点。

谢谢。

Answer 1

你必须更新系统/数据库/DB_Driver.php 文件。

您只需在此文件中进行 3 处小更改，这非常简单。

1) 在 Construction 内部添加您的读写服务器凭据。

        $this->server_details['local_server']['hostname'] = "localhost";
        $this->server_details['local_server']['username'] = "select_user";
        $this->server_details['local_server']['password'] = "password";       

        $this->server_details['live_server']['hostname'] = "192.192.223.22";  
        $this->server_details['live_server']['username'] = "write_user"; 
        $this->server_details['live_server']['password'] = "password";        

2) Create New 函数将切换数据库连接以进行 select 和 write 查询。

 private function ebrandz_switch_db_for_read_write($sql) {               

       if( $this->hostname == $this->server_details['local_server']['hostname'] &&  $this->username == $this->server_details['local_server']['username'] &&  $this->password == $this->server_details['local_server']['password'] ) {    
                   //echo $sql.'<br/>';
         if(stristr($sql, 'SELECT')) {   
                            foreach($this->server_details['local_server'] as $index_key => $index_value ) { 
                                $this->$index_key = $index_value;  
                            }             

                              $this->conn_id = null;  //unset resource link 
                              $this->initialize();   //Reinitialize connnection with new parameters                                                                                                       

                    } else {    
                            //die('write operation is not allowed.');
                            foreach($this->server_details['live_server'] as $index_key => $index_value ) { 
                                 $this->$index_key = $index_value;  
                            }  
                            $this->conn_id = null ; //unset resource link 
                            $this->initialize();    //Reinitialize connnection with new parameters                                                           
                    }

               } else if( $this->hostname == $this->server_details['live_server']['hostname'] &&  $this->username == $this->server_details['live_server']['username']  &&  $this->password ==  $this->server_details['live_server']['password'] ) {  

                    if(stristr($sql, 'SELECT')) { 
                            foreach($this->server_details['local_server'] as $index_key => $index_value ) { 
                                 $this->$index_key = $index_value;  
                            }  

                            $this->conn_id = null ;  //unset resource link 
                            $this->initialize();     //Reinitialize connnection with new parameters      

                    } else {  
                            //die('write operation is not allowed.');
                            foreach($this->server_details['live_server'] as $index_key => $index_value ) { 
                                 $this->$index_key = $index_value;
                            } 

                            $this->conn_id = null ; //unset resource link 
                            $this->initialize();    //Reinitialize connnection with new parameters                                                           
                    }

               }

               //Code to re initialize the connection 
    }

3) 在这个文件的查询函数中，你必须调用之前定义的函数。

// Verify table prefix and replace if necessary
    if ($this->dbprefix !== '' && $this->swap_pre !== '' && $this->dbprefix !== $this->swap_pre)
    {
        $sql = preg_replace('/(\W)'.$this->swap_pre.'(\S+?)/', '\\1'.$this->dbprefix.'\\2', $sql);
    }

     /**
     * @author Anant Waykar
     * if query is read only then load some other database
     */
            $this->ebrandz_switch_db_for_read_write($sql);                     
      //Code to re initialize the connection 

Answer 2

你应该在`application/config/database.php'中提供第二个数据库信息

通常，您会设置默认数据库组，如下所示：

$db['default']['hostname'] = "localhost";
$db['default']['username'] = "root";
$db['default']['password'] = "";
$db['default']['database'] = "database_name";
$db['default']['dbdriver'] = "mysql";
$db['default']['dbprefix'] = "";
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = FALSE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci";
$db['default']['swap_pre'] = "";
$db['default']['autoinit'] = TRUE;
$db['default']['stricton'] = FALSE;

请注意，登录信息和设置在名为 $db['default'] 的数组中提供。

然后您可以在新数组中添加另一个数据库 - 我们称之为“otherdb”。

$db['otherdb']['hostname'] = "localhost";
$db['otherdb']['username'] = "root";
$db['otherdb']['password'] = "";
$db['otherdb']['database'] = "other_database_name";
$db['otherdb']['dbdriver'] = "mysql";
$db['otherdb']['dbprefix'] = "";
$db['otherdb']['pconnect'] = TRUE;
$db['otherdb']['db_debug'] = FALSE;
$db['otherdb']['cache_on'] = FALSE;
$db['otherdb']['cachedir'] = "";
$db['otherdb']['char_set'] = "utf8";
$db['otherdb']['dbcollat'] = "utf8_general_ci";
$db['otherdb']['swap_pre'] = "";
$db['otherdb']['autoinit'] = TRUE;
$db['otherdb']['stricton'] = FALSE;

如果您需要同时连接多个数据库，您可以这样做：

$readDB = $this->load->database('otherdb', TRUE);

//For read:
$query = $readDB->select('first_name, last_name')->get('person');
var_dump($query);

//For write:
$this->db->insert('tablename', $insert_array);