Laravel 迁移 - 删除列
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Laravel Migrations - Dropping columns
提问by Black
I need to drop the column UserDomainNamefrom my database table clients.
我需要UserDomainName从我的数据库表中删除该列clients。
At first I installed doctrine/dbalby executing composer require doctrine/dbalfollowed by composer update, like described in the documentation.
起初我doctrine/dbal通过执行composer require doctrine/dbal然后执行安装composer update，就像文档中描述的那样。
Then I created the migration which I want to use to drop the column:
然后我创建了我想用来删除列的迁移：
php artisan make:migration remove_user_domain_name_from_clients --table=clients
I added Schema::dropColumn('UserDomainName');to the down()method:
我添加Schema::dropColumn('UserDomainName');到down()方法中：
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class RemoveDomainName extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::table('clients', function (Blueprint $table) {
//
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::table('clients', function (Blueprint $table) {
Schema::dropColumn('UserDomainName');
});
}
}
However, I get
但是，我得到
Migrating: 2017_08_22_135145_remove_user_domain_name_from_clients
Migrated: 2017_08_22_135145_remove_user_domain_name_from_clients
after executing php artisan migratebut no Column is dropped.
If I execute it again I get Nothing to migrate.
执行后php artisan migrate但没有删除列。如果我再次执行它，我会得到Nothing to migrate.
回答by Jerodev
The downfunction is used for rollbacks, you have to add this dropColumnin the upfunction because it is an action you want to perform when running migrations.
该down函数用于回滚，您必须dropColumn在up函数中添加它，因为这是您在运行迁移时要执行的操作。
So, in your upfunction there should be:
所以，在你的up函数中应该有：
Schema::table('clients', function (Blueprint $table) {
$table->dropColumn('UserDomainName');
});
And in the downfunction you should do the inverse, add the column back:
在down你应该做的相反的函数中，将列添加回来：
Schema::table('clients', function (Blueprint $table) {
$table->string('UserDomainName');
});
This way, you can always return to any point in the migrations.
这样，您始终可以返回到迁移中的任何一点。
