时间戳/ 1 函数接受选项关键字列表，您可以使用它设置默认值。

The timestamps/1 function accepts an options keyword list, you can set the default value with it.

def change do
  alter table(:channels) do
    timestamps default: "2016-01-01 00:00:01", null: false
  end
end

UPDATE Ecto> = 2.1

您需要使用新的类型 NaiveDateTime

def change do
  alter table(:channels) do
    timestamps default: ~N[2017-01-01 00:00:01], null: false
  end
end

如果您还有更多疑问，请查看文档

If you have more doubts take a look at the documentation