Laravel - Migration (Adding indexes to tables throws an error)

Question

I have made a migration file where I am adding indexes to existing columns in my database. This is my migration file:

public function up()
    {
        Schema::table('alternatives', function (Blueprint $table){
            $table->index('question_id');
            $table->index('correct');
        });

        Schema::table('answers', function (Blueprint $table){
            $table->index(['question_id', 'player_id']);
            $table->index('quiz_id');
        });

        Schema::table('players', function (Blueprint $table){
            $table->index('nickname');
        });

        Schema::table('player_quiz', function (Blueprint $table){
            $table->index('player_id');
            $table->index('quiz_id');
        });

        Schema::table('question_quiz', function (Blueprint $table){
            $table->index('question_id');
            $table->index('quiz_id');
            $table->index('start_time');
            $table->index('active_time');
            $table->index('finish_time');
        });

        Schema::table('question_subject', function (Blueprint $table){
            $table->index('question_id');
            $table->index('subject_id');
        });

        Schema::table('question_topic', function (Blueprint $table){
            $table->index('question_id');
            $table->index('topic_id');
        });

        Schema::table('question_year', function (Blueprint $table){
            $table->index('question_id');
            $table->index('year_id');
        });

        Schema::table('quiz_subject', function (Blueprint $table){
            $table->index('quiz_id');
            $table->index('subject_id');
        });

        Schema::table('quiz_topic', function (Blueprint $table){
            $table->index('quiz_id');
            $table->index('topic_id');
        });

        Schema::table('quiz_year', function (Blueprint $table){
            $table->index('quiz_id');
            $table->index('year_id');
        });

        Schema::table('quizzes', function (Blueprint $table){
            $table->index('code');
            $table->index('token');
            $table->index('status');
        });

        Schema::table('subjects', function (Blueprint $table){
            $table->index('name');
        });

        Schema::table('topics', function (Blueprint $table){
            $table->index('name');
        });

        Schema::table('years', function (Blueprint $table){
            $table->index('name');
        });
    }

But when I run php artisan migrate I get an error:

[Illuminate\Database\QueryException]
SQLSTATE[42000]: Syntax error or access violation: 1061 Duplicate key name 'alternatives_question_id_index' (SQL: alter table alternatives add index alternatives _question_id_index(question_id))

[PDOException]
SQLSTATE[42000]: Syntax error or access violation: 1061 Duplicate key name 'alternatives_question_id_index'

Which is weird since I don't have an already existing index for alternatives table and even when I delete that line, I get the same error for the 'correct' column as well, which also doesn't have any index from before. I get the same error for all the columns in 'answers' table too.

I am using Laravel 5.2 and mysql Ver 14.14.

And this is how my migration file for creating 'alternatives' table looks like:

public function up()
    {
        Schema::create('alternatives', function (Blueprint $table) {
            $table->timestamps();
            $table->increments('id');
            $table->string('text');
            $table->boolean('correct');
            $table->integer('question_id');
        });


        Schema::table('alternatives', function ($table) {
          $table->dropColumn('created_at');
          $table->dropColumn('updated_at');
        });

        Schema::table('alternatives', function ($table) {
          $table->integer('created_at');
          $table->integer('updated_at');
        });
    }

Answer 1

This is a quite typical situation when modifications of several tables combined in one migration. It seems that when you ran the migration first time you created indexes in the table 'alternatives'. However, somewhere in the middle your script failed. In this case Laravel doesn't make auto-rollback of all previous executed commands. It means that next time your migration fails on the first command. So I suggest you to run rollback manually, split big migration in small one dedicated for each table.