Entity Framework 不支持DefaultValue

http://*.com/questions/18506088/entityframework-not-updating-column-with-default-value

Yes, you can't do this. You have to set the default in code. There's no real way around this.

More discussion about this here:

How to use Default column value from DataBase in Entity Framework?

有一个答案要求添加[DatabaseGenerated(DatabaseGeneratedOption.Identity)]

加完之后，发现没有啥用

public class SomeTable
{
    ...

    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public DateTime CreatedDate { get; set; }

    ...
}

结论：

这种有默认值的，只能通过自己在代码中设置对应实体的初始值，数据库的约束不起作用