MySQL-TIMESTAMP(3)的默认值 [英] MySQL - default value for TIMESTAMP(3)

问题描述

我的数据库是MySql 5.6.

My database is MySql 5.6.

我想使用CURRENT_TIMESTAMP作为类型为TIMESTAMP(3)的属性的默认值.

I want to use CURRENT_TIMESTAMP as the default value an attribute which is type of TIMESTAMP(3).

但是我得到了错误:

错误1067(42000):更新"的默认值无效

ERROR 1067 (42000): Invalid default value for 'updated'

我认为这是因为CURRENT_TIMESTAMP仅精确到秒.

I think it is because CURRENT_TIMESTAMP is only in precision of second.

如何将小数部分timestamp的当前时间设置为默认值?

How can I set current time as the default value for a timestamp with fractional part?

推荐答案

根据timestamp和datetime类型列上的文档:

As per documentation on timestamp and datetime type columns:

如果TIMESTAMP或DATETIME列定义在任何地方都包含显式的小数秒精度值，则在整个列定义中都必须使用相同的值.

If a TIMESTAMP or DATETIME column definition includes an explicit fractional seconds precision value anywhere, the same value must be used throughout the column definition.

这是允许的:

CREATE TABLE t1 (
  ts TIMESTAMP(6) DEFAULT CURRENT_TIMESTAMP(6) ON UPDATE CURRENT_TIMESTAMP(6)
);

其他示例:

mysql> create table tbl_so_q23671222_1( ts timestamp(3) default now() );
ERROR 1067 (42000): Invalid default value for 'ts'

mysql> create table tbl_so_q23671222_1( ts timestamp(3) default now(3) );
Query OK, 0 rows affected (0.59 sec)

mysql> create table tbl_so_q23671222_2( ts timestamp(3) default current_timestamp );
ERROR 1067 (42000): Invalid default value for 'ts'

mysql> create table tbl_so_q23671222_2( ts timestamp(3) default current_timestamp(3) );
Query OK, 0 rows affected (0.38 sec)

mysql> desc tbl_so_q23671222_1;
+-------+--------------+------+-----+----------------------+-------+
| Field | Type         | Null | Key | Default              | Extra |
+-------+--------------+------+-----+----------------------+-------+
| ts    | timestamp(3) | NO   |     | CURRENT_TIMESTAMP(3) |       |
+-------+--------------+------+-----+----------------------+-------+
1 row in set (0.01 sec)

mysql> desc tbl_so_q23671222_2;
+-------+--------------+------+-----+----------------------+-------+
| Field | Type         | Null | Key | Default              | Extra |
+-------+--------------+------+-----+----------------------+-------+
| ts    | timestamp(3) | NO   |     | CURRENT_TIMESTAMP(3) |       |
+-------+--------------+------+-----+----------------------+-------+
1 row in set (0.01 sec)

参考:
TIMESTAMP和DATETIME的初始化和更新 >

这篇关于MySQL-TIMESTAMP(3)的默认值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！