是否可以在Laravel的String / varchar类型的列的两个表之间创建外键关系？

Question

I have a categories table which has an id and a slug(varchar type) column.I want to create a subcategories table which will have a column category_slug(varchar type) that will reference the slug column in the Category table.

I am getting errors during php artisan migrate.

    Schema::create('subcategories', function (Blueprint $table) {
        $table->increments('id');
        $table->string('category_slug')->unique();
        $table->integer('product_id');
        $table->foreign('category_slug')
       ->references('slug')->on('categories');
        $table->timestamps();
  });

The errors in the terminal are.

[Illuminate\\Database\\QueryException] SQLSTATE[HY000]: General error: 1005 Can't create table laravel_eshopper . #sql-ee8_272 (errno: 150 "Foreign key constraint is incorrectly formed") (SQL: alter table tabpanes add constraint tabpanes_category_slug_foreign foreign key ( category_slug ) references categories ( slug ))

[PDOException] SQLSTATE[HY000]: General error: 1005 Can't create table laravel_eshopper . #sql-ee8_272 (errno: 150 "Foreign key constraint is incorrectly formed")

Answer 1

Yes Surely You can do that See the Example Below:

Suppose you have your category table as below:

  Schema::create('categories', function (Blueprint $table) {
        $table->increments('id');
        $table->string('slug')->unique();
        $table->timestamps();
  });

Now You can create subcategories with foreign key as below:

 Schema::create('subcategories', function (Blueprint $table) {
        $table->increments('id');
        $table->string('category_slug')->unique();
        $table->foreign('category_slug')
       ->references('slug')->on('categories')->onUpdate('cascade')
        ->onDelete('cascade');
        $table->timestamps();
  });