codeigniter db操作方法

• 链接数据库
• ——-
• $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
• ——-
• //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
• $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
• —————————————————–
• 插入
• ——-
• $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
• ——-
• $data = array(
• ‘name’ => $name,
• ‘email’ => $email
• );
• $where = “id = 1″;
• $this->db->update(‘tablename’, $data);
• $this->db->update_string(‘tablename’, $data, $where);
• —————————————————–
• 删除
• ——-
• $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