table foreign in laravel code example

Example 1: laravel migration foreign key 5.6

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

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

Example 2: migrate to an existing table in laravel commad

public function up()
{
    Schema::table('users', function($table) {
        $table->integer('paid');
    });
}