codeigniter中DB类的用法收集

3. 链接数据库

4. -------
5. $this->load->database();//手动连接数据库
6. //连接多数据库
7. $DB1 = $this->load->database('group_one', TRUE);
8. $DB2 = $this->load->database('group_two', TRUE);

9. 查询

10. -------
11. //参数绑定形式
12. $sql = "SELECT * FROM some_table WHERE id = ? AND status = ? AND author = ?";
13. $this->db->query($sql, array(3, 'live', 'Rick'));
14. //多结果标准查询
15. $query = $this->db->query($sql); //自定义
16. $query = $this->db->get('tablename'); //便捷形式，相当于:SELECT * FROM tablename
17. $query = $this->db->get('tablename', 10, 20); // 相当于: SELECT * FROM tablename LIMIT 20, 10
18. $query->result() //对象形式
19. $query->result_array() //数组形式
21. $query->num_rows() //总条数
22. $query->num_fields() //字段数
23. //单结果标准查询
24. $row = $query->row(); //对象形式
25. $row = $query->row_array(); //数组形式
27. 插入
28. -------
29. $data = array(
30. 'title' => $title,
31. 'name' => $name
32. );
33. $this->db->insert('tablename', $data); //便捷插入
34. $this->db->insert_string('tablename', $data); //便捷插入
35. $this->db->insert_id() //刚插入的id
36. $this->db->affected_rows() //影响的行数(update,insert)

37. 更新

38. -------
39. $data = array(
40. 'name' => $name,
41. 'email' => $email
42. );
43. $where = "id = 1";
44. $this->db->update('tablename', $data);
45. $this->db->update_string('tablename', $data, $where);

46. 删除

47. -------
48. $array = array(
49. 'name' => $name,
50. 'title' => $title
51. );
52. $this->db->delete('tablename', $array);
53. // Produces:
54. // "DELETE FROM tablename WHERE name = '$name' AND title = '$title'"
55. $this->db->truncate('tablename'); //清空表
56. // Produce: TRUNCATE tablename

57. （where）

58. -------
59. $array = array(
60. 'name' => $name,
61. 'title' => $title
62. );
63. $this->db->where($array);
64. // Produces: "WHERE name = '$name' AND title = '$title'"
65. -----------------------------------------------------
66. $this->db->count_all('tablename'); //表中记录总行数
67. -----------------------------------------------------
68. $query->free_result() //释放资源

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