Laravel迁移更改并使列为空 [英] Laravel migration change and make column nullable

问题描述

我创建了一个具有user_id unsigned的迁移。如何在新的联盟中编辑user_id以使其成为 nullable（）？

I created a migration with user_id unsigned. How can I edit user_id in a new migation to also make it nullable() ?

    Schema::create('throttle', function(Blueprint $table)
    {
        $table->increments('id');
        $table->integer('user_id')->unsigned(); // this needs to also be nullable, how should the next migration be?
    }

推荐答案

我假设您正在编辑已经添加了数据的列，因此删除列并再次添加为可空列不可能没有丢失数据，我们将 alter 现有的列。

I assume that you're trying to edit a column that you have already added data on, so dropping column and adding again as a nullable column is not possible without losing data. We'll alter the existing column.

然而，Laravel的模式构建器不支持修改列，而不是重命名列
所以你需要运行原始查询来执行，如下所示：

However, Laravel's schema builder does not support modifying columns other than renaming the column. So you will need to run raw queries to do them, like this:

function up()
{
    DB::statement('ALTER TABLE `throttle` MODIFY `user_id` INTEGER UNSIGNED NULL;');
}

为确保您仍可以回滚迁移，我们将执行 down（）。

And to make sure you can still rollback your migration, we'll do the down() as well.

function down()
{
    DB::statement('ALTER TABLE `throttle` MODIFY `user_id` INTEGER UNSIGNED NOT NULL;');
}

一个注意事项是，由于您在可空和不可空转换之间，需要确保在迁移之前/之后清理数据。这样做在您的迁移脚本中有两种方式：

One note is that since you are converting between nullable and not nullable, you'll need to make sure you clean up data before/after your migration. So do that in your migration script both ways:

function up()
{
    DB::statement('ALTER TABLE `throttle` MODIFY `user_id` INTEGER UNSIGNED NULL;');
    DB::statement('UPDATE `throttle` SET `user_id` = NULL WHERE `user_id` = 0;');
}

function down()
{
    DB::statement('UPDATE `throttle` SET `user_id` = 0 WHERE `user_id` IS NULL;');
    DB::statement('ALTER TABLE `throttle` MODIFY `user_id` INTEGER UNSIGNED NOT NULL;');
}

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