即使不存在必需字段，MySQL 也允许插入

Question

我有一个用户的数据库表，其设置与此类似:

+---------------------+--------------+------+-----+------------+----------------+
| Field               | Type         | Null | Key | Default    | Extra          |
+---------------------+--------------+------+-----+------------+----------------+
| id_user             | int(5)       | NO   | PRI | NULL       | auto_increment |
| login               | varchar(50)  | NO   |     |            |                |
| password            | varchar(50)  | NO   |     |            |                |
| address             | varchar(255) | NO   |     | NULL       |                |
+---------------------+--------------+------+-----+------------+----------------+

由于地址字段设置为非空并且默认为空，这应该有效地使地址字段成为必需的，对吧？

但是当我执行如下查询时:

INSERT INTO mydatabase.users
SET
    mydatabase.users.login='test_username',
    mydatabase.users.password='test_password'

它成功地拯救了用户，没有提示地址字段被设置为空白。

这可能是什么原因造成的？我预计在这种情况下会出现错误。我已经在 MySQL 5.5 和 5.6 上试过了。

Answer 1

Strict SQL mode配置文件中没有启用，因此mysql放宽了对数据插入的某些控制:

Strict mode controls how MySQL handles invalid or missing values in data-change statements such as INSERT or UPDATE. A value can be invalid for several reasons. For example, it might have the wrong data type for the column, or it might be out of range. A value is missing when a new row to be inserted does not contain a value for a non-NULL column that has no explicit DEFAULT clause in its definition. (For a NULL column, NULL is inserted if the value is missing.) Strict mode also affects DDL statements such as CREATE TABLE.