当我运行php artisan migration命令时出错

Question

I am trying to add a commenting system on my blog application however I get this error when trying to run comment migration which seems to have nothing to do with my current comments migration file, but a previous post_tag migration file

[Illuminate\Database\QueryException]
SQLSTATE[42S01]: Base table or view already exists: 1050 Table 'post_tag' already exists (SQL:
    create table `post_tag` (
      `id` int unsigned not null  auto_increment primary key,
      `post_id` int unsigned not null, 
      `tag_id` int unsigned not null
    ) default character set utf8 collate utf8_unicode_ci) 

This is my comments migration file

<?php

//2017_01_16_101128_create_comments_table.php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCommentsTable extends Migration
{
/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    Schema::create('comments', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name');
        $table->string('email');
        $table->text('comment');
        $table->boolean('approved');
        $table->integer('post_id')->unsigned();
        $table->timestamps();

    });

    Schema::table('comments', function($table){
            $table->foreign('post_id')->references('id')->on('posts')->
                     onDelete('cascade');
        });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    Schema::dropForeign(['post_id']);
    Schema::drop('comments');
}
}

and this is my post_tag migration file

<?php

2016_12_18_230831_create_post_tag_table.php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreatePostTagTable extends Migration
{
/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    Schema::create('post_tag', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('post_id')->unsigned();
        $table->foreign('post_id')->references('id')->on('posts');
        $table->integer('tag_id')->unsigned();
        $table->foreign('tag_id')->unsigned();
    });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    Schema::drop('post_tag');
}
}

How do I get rid of this error or what am I missing here?

Answer 1

You would have to manually drop the table in mysql:

mysql> drop table post_tag;

Then run the migration again

php artisan migrate

Answer 2

In your CreatePostTagTable migration you may wont to change

$table->integer('tag_id')->unsigned();
$table->foreign('tag_id')->unsigned();

to

$table->integer('tag_id')->unsigned();
$table->foreign('tag_id')->references('id')->on('tag');

There was a duplication.

Then manually remove post_tag table. It could have be created once again. You may also want to check on your migration table in your database as there could be a record of. post_tag table. If so remove it. Then you could run migration safely.

Additionally since you are creating a pivot table you don't probably gonna need a $table->increments('id'); . It could be depend on your situation. In most cases you don't need it.

Answer 3

I think you should try this:

Drop table post_tag;

AND

Delete post_tag migration from migrations table

After run the migration

php artisan migrate

Hope this work for you!