ci高級用法篇之連接多個數據庫

2015年07月26日 16:27:40 dongxie548 閱讀數：6225

在我們的項目中有時可能需要連接不止一個數據庫，在ci中如何實現呢？

我們在本地新建了兩個數據庫，如下截圖所示：

修改配置文件database.php文件爲如下格式（讀者根據自己數據庫的情況修改相應參數的配置）：

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
/*
| -------------------------------------------------------------------
| DATABASE CONNECTIVITY SETTINGS
| -------------------------------------------------------------------
| This file will contain the settings needed to access your database.
|
| For complete instructions please consult the 'Database Connection'
| page of the User Guide.
|
| -------------------------------------------------------------------
| EXPLANATION OF VARIABLES
| -------------------------------------------------------------------
|
| ['dsn'] The full DSN string describe a connection to the database.
| ['hostname'] The hostname of your database server.
| ['username'] The username used to connect to the database
| ['password'] The password used to connect to the database
| ['database'] The name of the database you want to connect to
| ['dbdriver'] The database driver. e.g.: mysqli.
| Currently supported:
| cubrid, ibase, mssql, mysql, mysqli, oci8,
| odbc, pdo, postgre, sqlite, sqlite3, sqlsrv
| ['dbprefix'] You can add an optional prefix, which will be added
| to the table name when using the Query Builder class
| ['pconnect'] TRUE/FALSE - Whether to use a persistent connection
| ['db_debug'] TRUE/FALSE - Whether database errors should be displayed.
| ['cache_on'] TRUE/FALSE - Enables/disables query caching
| ['cachedir'] The path to the folder where cache files should be stored
| ['char_set'] The character set used in communicating with the database
| ['dbcollat'] The character collation used in communicating with the database
| NOTE: For MySQL and MySQLi databases, this setting is only used
| as a backup if your server is running PHP < 5.2.3 or MySQL < 5.0.7
| (and in table creation queries made with DB Forge).
| There is an incompatibility in PHP with mysql_real_escape_string() which
| can make your site vulnerable to SQL injection if you are using a
| multi-byte character set and are running versions lower than these.
| Sites using Latin-1 or UTF-8 database character set and collation are unaffected.
| ['swap_pre'] A default table prefix that should be swapped with the dbprefix
| ['encrypt'] Whether or not to use an encrypted connection.
| ['compress'] Whether or not to use client compression (MySQL only)
| ['stricton'] TRUE/FALSE - forces 'Strict Mode' connections
| - good for ensuring strict SQL while developing
| ['failover'] array - A array with 0 or more data for connections if the main should fail.
| ['save_queries'] TRUE/FALSE - Whether to "save" all executed queries.
| NOTE: Disabling this will also effectively disable both
| $this->db->last_query() and profiling of DB queries.
| When you run a query, with this setting set to TRUE (default),
| CodeIgniter will store the SQL statement for debugging purposes.
| However, this may cause high memory usage, especially if you run
| a lot of SQL queries ... disable this to avoid that problem.
|
| The $active_group variable lets you choose which connection group to
| make active. By default there is only one group (the 'default' group).
|
| The $query_builder variables lets you determine whether or not to load
| the query builder class.
*/
$active_group = 'test';//默認連接test數據庫
$active_record = TRUE;//是否開啓active record
$db['test'] = array(
'dsn' => '',
'hostname' => 'localhost',
'username' => 'root',
'password' => '',
'database' => 'test',
'dbdriver' => 'mysqli',
'dbprefix' => '',
'pconnect' => FALSE,
'db_debug' => TRUE,
'cache_on' => FALSE,
'cachedir' => '',
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
'swap_pre' => '',
'encrypt' => FALSE,
'compress' => FALSE,
'stricton' => FALSE,
'failover' => array(),
'save_queries' => TRUE
);
//test2數據庫相關配置
$db['test2'] = array(
'dsn' => '',
'hostname' => 'localhost',
'username' => 'root',
'password' => '',
'database' => 'test2',
'dbdriver' => 'mysqli',
'dbprefix' => '',
'pconnect' => FALSE,
'db_debug' => TRUE,
'cache_on' => FALSE,
'cachedir' => '',
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
'swap_pre' => '',
'encrypt' => FALSE,
'compress' => FALSE,
'stricton' => FALSE,
'failover' => array(),
'save_queries' => TRUE
);

在applicaton/model目錄下創建兩個文件：score.php

<?php
class Score extends CI_Model {
private $tableName = 'score';
function __construct()
{
parent::__construct();
}
public function getAllScores(){
return $this->db->get($this->tableName);
}
}

和students.php

<?php
class Students extends CI_Model {
private $tableName = 'students';
function __construct()
{
parent::__construct();
}
public function getAllStudents(){
return $this->db->get($this->tableName);
}
}

修改welcome控制器：

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Welcome extends ci_Controller {
/**
* Index Page for this controller.
*
* Maps to the following URL
* http://example.com/index.php/welcome
* - or -
* http://example.com/index.php/welcome/index
* - or -
* Since this controller is set as the default controller in
* config/routes.php, it's displayed at http://example.com/
*
* So any other public methods not prefixed with an underscore will
* map to /index.php/welcome/<method_name>
* @see http://codeigniter.com/user_guide/general/urls.html
*/
public function __construct(){
parent::__construct();
$this->load->model('students');
$this->load->model('score');
}
public function index()
{
var_dump($this->students->getAllStudents()->result());
var_dump($this->score->getAllScores()->result());
die('測試結束');
}
}

訪問http://localhost/ci2/地址，瀏覽器輸出如下截圖所示：

可以看到ci沒有找到score表，我們需要在score.php文件中用

$this->db = $this->load->database('test2', TRUE);

顯示指明score所在的數據庫：

<?php
class Score extends CI_Model {
private $tableName = 'score';
private $db;
function __construct()
{
parent::__construct();
$this->db = $this->load->database('test2', TRUE);
}
public function getAllScores(){
return $this->db->get($this->tableName);
}
}

再次訪問訪問http://localhost/ci2/地址，輸出結果如下截圖所示：

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