MySQL：关于列的 NULL 和 NOT NULL
创建一个测试表：
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mysql> use test; Database changed mysql> show tables; Empty set (0.00 sec) mysql> create table people -> ( -> id int, -> name varchar(40), -> sex varchar(10), -> comment varchar(900) -> ); Query OK, 0 rows affected (0.35 sec) mysql> |
看看这时候的表结构：
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mysql> desc people; +---------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------+--------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | name | varchar(40) | YES | | NULL | | | sex | varchar(10) | YES | | NULL | | | comment | varchar(900) | YES | | NULL | | +---------+--------------+------+-----+---------+-------+ 4 rows in set (0.02 sec) mysql> |
可以看到，这个时候是没有非空约束的，所以，你可以有的列不插入值：
[crayon-63e279aa377178[……]
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Author:
Adamhuan
- Categories: MySQL
- Tags: Column, ERROR 1265 (01000): Data truncated for column 'sex' at row 1, ERROR 1364 (HY000): Field 'sex' doesn't have a default value, MySQL, NULL, 约束, 非空
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