mysql - 创建新数据库表时不能在 DEFAULT 约束中使用函数和变量

Question

我正在尝试使用 CREATE 命令创建一个新数据库。这是 SQL:

CREATE TABLE test(
rok_utworzenia timestamp DEFAULT CURRENT_DATE
);

但是它会抛出一个错误

'#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CURRENT_DATE )' at line 2'

如果我将 DEFAULT 约束更改为常量，它会起作用，但如果我尝试使用任何函数或变量，则不会。为什么会这样？

Answer 1

使用这个:

CREATE TABLE test( rok_utworzenia timestamp DEFAULT CURRENT_TIMESTAMP );

来自MySQL site :

The DEFAULT value clause in a data type specification indicates a default value for a column. With one exception, the default value must be a constant; it cannot be a function or an expression. This means, for example, that you cannot set the default for a date column to be the value of a function such as NOW() or CURRENT_DATE. The exception is that you can specify CURRENT_TIMESTAMP as the default for a TIMESTAMP column.