如何在codeigniter中更新列设置为NULL的表

Question

i have a problem with update column with set data to NULL, i have a table user with each one column is id_parent column, user can delete parent and can add parent, so if user have a parent , id_parent will set with user's parent id , but user can delete parent's data, so if user delete parent's data, id_parent column, will set to NULL. so how to set data to null in database not " " but NULL . here's my user table.

user

id_user | name | address | id_parent

Answer 1

使用它来设置空列。它会起作用，不要忘记在活动记录的第三个参数 SET 上添加 false

$this->db->set('id_parent', 'NULL', false);

Answer 2

you can try this code in 'model', hope it'll work:

public function update_std_marks($id_user) {

    $this->db->set('id_parent', null);
    $this->db->where('id_user', $id_user);
    $this->db->update('user');
}

Answer 3

I was curious so I wanted to see how CodeIgniter's Active Record would handle different variations of syntax when working with a null value. I'll map out several test cases for where() and set() method calls.

Battery of where() tests:

1.  ->where('col', null) // `col` IS NULL

2.  ->where('col', null, false) // col IS NULL

3.  ->where('col', 'NULL') // `col` = 'NULL'

4.  ->where('col', 'NULL', false) // col = NULL

5.  ->where('col IS NULL') // `col` IS NULL

6.  ->where('col IS NULL', null) // `col` IS NULL

7.  ->where('col IS NULL', null, false) // col IS NULL

8.  ->where('col', 'IS NULL') // `col` 'IS NULL'

9.  ->where('col', 'IS NULL', false) // col = IS NULL

Properly quoted and formed: #1, #5, #6 ( recommended )
Logically formed, but not quoted: #2, #7 ( not recommended )
Inappropriate rendered syntax: #3, #4, #8, #9 ( do not use )

---

Battery of set() tests:

1.  ->set('col', null) // `col` = NULL

2.  ->set('col', null, false) // col =

3.  ->set('col', 'NULL') // `col` = 'NULL'

4.  ->set('col', 'NULL', false) // col = NULL

5.  ->set('col IS NULL') // `col IS` `NULL` = ''

6.  ->set('col IS NULL', null) // `col IS` `NULL` = NULL

7.  ->set('col IS NULL', null, false) // col IS NULL =

8.  ->set('col', 'IS NULL') // `col` = 'IS NULL'

9.  ->set('col', 'IS NULL', false) // col = IS NULL

Properly quoted and formed: #1 ( recommended )
Logically formed, but not quoted: #4 ( not recommended )
Inappropriate rendered syntax: #2, #3, #5, #6, #7, #8, #9 ( do not use )

Answer 4

Your user table must have the attribute set to is_null in the id_parent field. Otherwise you can't.

The query should be something like

Update table user set id_parent = null where id_user = X

You can set that column nullable with this query:

ALTER TABLE user MODIFY id_parent int(11) null;

Try this for codeigniter:

$fields = array(
                        'id_parent' => array(
                                                         'name' => 'id_parent',
                                                         'type' => 'INT',
                                                ),
);
$this->dbforge->modify_column('user', $fields);

or simply:

$this->db->query('ALTER TABLE user MODIFY id_parent int(11) null;');