Question

我试图在一次迁移中用主键创建外键。

这是针对Laravel 5.7的。我尝试了各种方法来实现自己的目标。这是我的最终代码。

    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');
    });

它以“ user_id”作为主键构成一个普通表，但它不是外键。

Answer 1

尝试此代码

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');
    }
}

现在，您想要在foriegn key表中的users表中将teachers设置为 id

我已清除

现在将列添加到techers表并添加foriegn键constarint

METHOD ONE

添加列

$table->unsignedInteger('user_id');

添加主键

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

现在的说明user_id是教师表references('id')中的字段名称，它引用的ID on('users')在用户表中

METHOD TWO

添加列

$table->integer('user_id');

添加主键

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

现在的说明user_id是教师表references('id')中的字段名称，它引用的ID on('users')在用户表中，unsigned()将unsignedinteger添加到列中

If Your issue is not solved kindly comment below

希望有帮助

Answer 4

您尝试过吗？

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');
});

我认为primary()不能像unique()那样链接到列定义上。

迁移Laravel无法同时创建主键和前键

4 个答案: