Unable to create multiple primary attributes

Question

How to define this relationship in Laravel ? I tried to develop three primary keys in Laravel. but it doesn't work. how could i resolve this ?

Answer 1

Those Keys may symbolise primary keys, foreign keys, unique columns or indexes.

You cannot have more than one primary key on a table.

Here is what I tried: Diagram

php .\artisan make:model Employee -m
php .\artisan make:model Title -m
php .\artisan make:model Salary -m

class CreateEmployeesTable extends Migration
{
    public function up(): void
    {
        Schema::create('employees', function (Blueprint $table) {
            $table->bigIncrements('emp_no');
            $table->string('first_name', 14);
            $table->string('last_name', 16);
            $table->date('birth_date');
            $table->date('hire_date');
        });
    }
};

class CreateTitlesTable extends Migration
{
    public function up(): void
    {
        Schema::create('titles', function (Blueprint $table) {
            $table->unsignedBigInteger('emp_no');
            $table->string('title', 50)->index();
            $table->date('from_date')->index();

            $table->foreign('emp_no')->references('emp_no')->on('employees');
        });
    }
};

class CreateSalariesTable extends Migration
{
    public function up(): void
    {
        Schema::create('salaries', function (Blueprint $table) {
            $table->unsignedBigInteger('emp_no');
            $table->integer('salary');
            $table->date('from_date')->index();

            $table->foreign('emp_no')->references('emp_no')->on('employees');
        });
    }
};

Edit

Assuming that multiple key icons mean a composite key

class CreateEmployeesTable extends Migration
{
    public function up(): void
    {
        Schema::create('employees', function (Blueprint $table) {
            $table->bigIncrements('emp_no');
            $table->string('first_name', 14);
            $table->string('last_name', 16);
            $table->date('birth_date');
            $table->date('hire_date');
        });
    }
};

class CreateTitlesTable extends Migration
{
    public function up(): void
    {
        Schema::create('titles', function (Blueprint $table) {
            $table->unsignedBigInteger('emp_no');
            $table->string('title', 50);
            $table->date('from_date');

            $table->foreign('emp_no')->references('emp_no')->on('employees');
            $table->primary(['emp_no', 'title', 'from_date']);
        });
    }
};

class CreateSalariesTable extends Migration
{
    public function up(): void
    {
        Schema::create('salaries', function (Blueprint $table) {
            $table->unsignedBigInteger('emp_no');
            $table->integer('salary');
            $table->date('from_date');

            $table->foreign('emp_no')->references('emp_no')->on('employees');
            $table->primary(['emp_no', 'from_date']);
        });
    }
};