無法通過遷移 Laravel 同時創建主鍵和前鍵

Question

我試圖在一次遷移時在主鍵中創建一個外鍵。

這適用於 Laravel 5.7。 我嘗試了不同的方法來嘗試實現我的目標。 這是我的最終代碼。

    Schema::create('teachers', function (Blueprint $table) {
        $table->engine = 'InnoDB';
        $table->integer('user_id')->unsigned()->primary();
        $table->timestamps();
    });

    Schema::table('teachers', function($table) {
        $table->foreign('user_id')
            ->references('id')
            ->on('users')
            ->onDelete('cascade');
    });

它制作了一個以“user_id”為主鍵的普通表，但它不是外鍵。

Answer 1

試試這個代碼

Schema::create('teachers', function (Blueprint $table) {
        $table->engine = 'InnoDB';
        $table->increments('id');
        $table->integer('user_id')->unsigned();
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
        $table->timestamps();
    });

Answer 2

Schema::create('teachers', function (Blueprint $table) {
    $table->engine = 'InnoDB';
    $table->integer('user_id')->unsigned()->nullable();
    $table->timestamps();
    $table->foreign('user_id')->references('id')->on('users')->onUpdate('cascade')->onDelete('cascade');
});

Answer 3

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateTeachersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        if (!Schema::hasTable('teachers')) 
        {
            Schema::create('teachers', function (Blueprint $table) {
                $table->increments('id');
                $table->string('teacher_name');
                $table->unsignedInteger('user_id');
                $table->timestamps();
                $table->foreign('user_id')->references('id')->on('users');

            });
        }       
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('teachers');
    }
}

現在你想在teachers表中設置作為users表的id的外foriegn key

我清楚嗎

現在將列添加到 techers 表並添加外鍵 constarint

METHOD ONE

添加列

$table->unsignedInteger('user_id');

添加主鍵

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

現在解釋user_id是教師表中的字段名稱references('id')正在引用 id on('users')在用戶表上

METHOD TWO

添加列

$table->integer('user_id');

添加主鍵

$table->foreign('user_id')->references('id')->on('users')->unsigned()->onDelete('cascade');

釋現在user_id在教師表中的字段名references('id')被引用id on('users')是用戶表， unsigned()將unsignedinteger列

If Your issue is not solved kindly comment below

希望能幫助到你

Answer 4

你試過這個嗎？

Schema::create('teachers', function (Blueprint $table) {
    $table->engine = 'InnoDB';
    $table->integer('user_id')->unsigned();
    $table->timestamps();

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

我不認為primary()可以像unique()那樣鏈接​​到列定義上。