用codeigniter也有一段时间了，一直没有做什么总结。现在总结一些Codeigniter操作数据库表的优化写法，虽说不全，但是也确实可以帮助那些刚刚上手CI的同学。

链接数据库

复制代码 代码如下:

$this->load->database();//手动连接数据库

//连接多数据库

$DB1 = $this->load->database('group_one', TRUE);

$DB2 = $this->load->database('group_two', TRUE);

查询

复制代码 代码如下:

//参数绑定形式

$sql = "SELECT * FROM some_table WHERE id = ? AND status = ? AND author = ?";

$this->db->query($sql, array(3, 'live', 'Rick'));

//多结果标准查询

$query = $this->db->query($sql); //自定义

$query = $this->db->get('tablename'); //便捷形式，相当于:SELECT * FROM tablename

$query = $this->db->get('tablename', 10, 20); // 相当于: SELECT * FROM tablename LIMIT 20, 10

$query->result() //对象形式

$query->result_array() //数组形式

/*

foreach ($query->result() as $row)

{

echo $row->title;

echo $row->name;

echo $row->email;

}

*/

$query->num_rows() //总条数

$query->num_fields() //字段数

//单结果标准查询

$row = $query->row(); //对象形式

$row = $query->row_array(); //数组形式

/*

$row = $query->row_array();

echo $row['name'];

*/

插入

复制代码 代码如下:

$data = array(

'title' => $title,

'name' => $name

);

$this->db->insert('tablename', $data); //便捷插入

$this->db->insert_string('tablename', $data);  //便捷插入

$this->db->insert_id() //刚插入的id

$this->db->affected_rows() //影响的行数(update,insert)

更新

复制代码 代码如下:

$data = array(

'name' => $name,

'email' => $email

);

$where = "id = 1";

$this->db->update('tablename', $data);

$this->db->update_string('tablename', $data, $where);

删除

复制代码 代码如下:

$array = array(

'name' => $name,

'title' => $title

);

$this->db->delete('tablename', $array);

// Produces:

// "DELETE FROM tablename WHERE name = '$name' AND title = "$title""

$this->db->truncate('tablename'); //清空表

// Produce: TRUNCATE tablename

-----------------------------------------------------

(where)

-------

$array = array(

'name' => $name,

'title' => $title

);

$this->db->where($array);

// Produces: "WHERE name = '$name' AND title = "$title""

-----------------------------------------------------

$this->db->count_all('tablename'); //表中记录总行数

-----------------------------------------------------

$query->free_result() //释放资源