mysql - Laravel 5 Mysql 重复条目错误

Question

我使用 Laravel 5 向数据库中插入一些条目，但出现以下错误:

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '1' for key 'category_id' (SQL: insert into products (product_name, product_price, category_id) values (asdaszzz, 123, 1))

据我了解，问题是我想在category_id表中添加的值已经存在于其他条目中，但问题是category_id表不是唯一键。下面我发布了迁移:

public function up()
{
    Schema::create('products', function($table)
    {
        $table->increments('id');
        $table->integer('category_id')->unsigned();
        $table->string('product_name', 255)->unique();
        $table->decimal('product_price', 10, 4);
        $table->dateTime('updated_at')->default(DB::raw('CURRENT_TIMESTAMP'));
    });

    Schema::table('products', function($table) {
        $table->foreign('category_id')->references('id')->on('categories');
    });
}

Answer 1

向category_id添加可为空

$table->integer('category_id')->unsigned()->nullable();