Answers for "laravel migration unsigned biginteger"

laravel foreign key

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

    $table->foreign('user_id')->references('id')->on('users');
});
OR
Schema::table('posts', function (Blueprint $table) {
    $table->foreignId('user_id')->constrained();
});

laravel migration table bigint

$this->bigIncrements('id');
This takes care of making it unsigned, auto increment and primary key