laravel - 如何使用Laravel迁移从列中删除唯一约束？

Question

我必须使用Laravel迁移从电子邮件列中删除唯一约束。这是我的代码:

class AlterEmailToUsers extends Migration
{
/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    Schema::table('users', function (Blueprint $table) {
        $table->string('email')->unique(false)->nullable()->change();
    });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    Schema::table('users', function (Blueprint $table) {
       $table->string('email')->nullable(false)->unique()->change();
    });
}

}

但是，当我运行php artisan migrate时，出现以下错误:

SQLSTATE[42000]: Syntax error or access violation: 1061 Duplicate key name 'users_email_unique' (SQL: alter table `users` add unique `users_email_unique`(`email`))

Answer 1

 public function up()
 {
   Schema::table('users', function (Blueprint $table) {
    $table->string('email')->unique(false)->nullable()->change();
   });
  }

改成

$table->dropUnique('users_email_unique');