Laravel - 它可能在表上添加外键，数据类型字符串是否未签名？

Question

i have two table, table universitas and table fakultas

on schema table universitas like below

public function up()
    {
        Schema::create('universitas', function (Blueprint $table) {
            $table->string('id');
            $table->string('nama_universitas');
            $table->timestamps();
        });
    }

and table fakultas like below

public function up()
    {
        Schema::create('fakultas', function (Blueprint $table) {
            $table->increments('id');
            $table->string('nama_fakultas');
            $table->string('nama_universitas')->unsigned();
            $table->foreign('nama_universitas')->references('id')->on('universitas');
            $table->string('keterangan');
            $table->timestamps();
        });
    }

its possible if i use data type string and use unsigned?

when i executed with php artisan migrate, i get an Error

Answer 1

The use of unsigned on a string makes no sense from a database perspective. The purpose of unsigned is to determine whether a numeric field can take negative values. For instance, a:

$table->tinyInteger('foo');

will create a database field that will take values between -128 and +128, whereas

$table->tinyInteger('foo')->unsigned();

will create a database field with the range 0 - 255

The important thing with your foreign keys is that the datatype of the foreign key must match the datatype of the primary key of the other table, whether it is a number or a string.