如何正确删除 Laravel 5.3 中用户表列中的“唯一”列属性？

Question

Following tutorials early on left me with a 'username' column that is set to unique. I would like to change that, so that my unique user identifier is tied to the email.

I've done the steps I found:

• composer require doctrine/dbal
• php artisan make:migration modify_users_table --table=users

My migration contains:

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

However, when I run the command 'php artisan migrate' I get

[Illuminate\\Database\\QueryException]
SQLSTATE[42000]: Syntax error or access violation: 1280 Incorrect index name '' (SQL: alter table users add unique (us
ername))

[Doctrine\\DBAL\\Driver\\PDOException]
SQLSTATE[42000]: Syntax error or access violation: 1280 Incorrect index name ''

[PDOException]
SQLSTATE[42000]: Syntax error or access violation: 1280 Incorrect index name ''

---

From my initial research it appears that the issue is with my index:

users_username_unique

So my question is:

Is it safe to remove that index, then run the migration?
If that is the correct way to do it, does my migration need to have something like this:

$table->dropUnique('users_username_unique');

Then will this command automatically create a correct, non-unique, index?

$table->string('username')->unique(false)->change();

Answer 1

For dropUnique() method, You have to create a new migration,

 Schema::table('users', function (Blueprint $table) {
         $table->dropUnique('username');  
 });

or If need, you can add a unique index for username.

Schema::table('users', function (Blueprint $table) {
        $table->unique('username');  
 });

Answer 2

Drop a unique index and add a plain index.

$table->dropUnique(['username']);
$table->index('username');  

If need, add a unique index for email.

$table->unique('email');

Database: Migrations

Answer 3

You need to create a new migration and use dropUnique() method:

Schema::table('users', function (Blueprint $table) {
    $table->dropUnique('users_username_unique');
});

Then run composer du and php artisan migrate commands to execute the migration.