Answers for "laravel database migration key"

foreign key laravel migration

$table->foreign('column_name')->references('id')->on('table_name')->onDelete('cascade');

create foreign key laravel migration

Schema::table('posts', function (Blueprint $table) {
    $table->unsignedBigInteger('user_id');

    $table->foreign('user_id')->references('id')->on('users');
});