Laravel 6 on Migration: SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint答案

【问题标题】：Laravel 6 on Migration: SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraintLaravel 6 on Migration: SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint
【发布时间】：2021-01-09 11:58:45
【问题描述】：

我正在尝试迁移我的表，但是当我进行 laravel 迁移时，会显示一个错误。

SQLSTATE[HY000]：一般错误：1215 无法添加外键约束（SQL：alter table subscribers 添加约束 subscribers_user_id_foreign 外键 (user_id) 引用 users (id) 在删除集 null )

这是我要迁移的表：

Schema::create('subscribers', function (Blueprint $table) {
            $table->increments('id');
            $table->string('account_no');
            $table->enum('type',['individual','company'])->default('individual');
            $table->string('title')->nullable();
            $table->string('firstname');
            $table->string('middlename');
            $table->string('lastname');
            $table->string('suffix')->nullable();
            $table->enum('gender',['male','female']);
            $table->date('birthday')->nullable();
            $table->string('contact_no');
            $table->string('email');
            $table->tinyInteger('status')->default(1);
            $table->integer('user_id')->unsigned();
            $table->unsignedInteger('created_by');
            $table->unsignedInteger('updated_by');
            $table->timestamps();

            $table->foreign('user_id')->references('id')->on('users')->onDelete('set null');
            $table->foreign('created_by')->references('id')->on('users')->onDelete('set null');
            $table->foreign('updated_by')->references('id')->on('users')->onDelete('set null');
        });

【问题讨论】：

你可以在这里找到答案stackoverflow.com/questions/22615926/…

标签： mysql laravel

【解决方案1】：

立即尝试

改变这个

$table->unsignedBigInteger('user_id');

Schema::create('subscribers', function (Blueprint $table) {
            $table->increments('id');
            $table->string('account_no');
            $table->enum('type',['individual','company'])->default('individual');
            $table->string('title')->nullable();
            $table->string('firstname');
            $table->string('middlename');
            $table->string('lastname');
            $table->string('suffix')->nullable();
            $table->enum('gender',['male','female']);
            $table->date('birthday')->nullable();
            $table->string('contact_no');
            $table->string('email');
            $table->tinyInteger('status')->default(1);
            $table->unsignedBigInteger('user_id');
            $table->unsignedInteger('created_by');
            $table->unsignedInteger('updated_by');
            $table->timestamps();

            $table->foreign('user_id')->references('id')->on('users')->onDelete('set null');
            $table->foreign('created_by')->references('id')->on('users')->onDelete('set null');
            $table->foreign('updated_by')->references('id')->on('users')->onDelete('set null');
        });

【讨论】：