Laravel 迁移添加外键给出错误外键 (`user_id`)

Question

当我 php artisan migrate 时出现错误，请参见下文。 Order migrations 是 users, companys 和 pivotmigration.

当我删除 user 时，所有 companies 都必须删除，当我删除 company 时，所有 users 都必须删除。

我做错了什么？

User.php

    Schema::create('users', function (Blueprint $table) {
        $table->engine = "InnoDB";
        $table->bigIncrements('id');
        $table->string('name');
        $table->string('email')->unique();
        $table->timestamp('email_verified_at')->nullable();
        $table->string('password');
        $table->rememberToken();
        $table->timestamps();
    });

Companies.php

    Schema::create('companies', function (Blueprint $table) {
        $table->engine = "InnoDB";
        $table->increments('id')->unsigned();
        $table->string('companyname');
        $table->string('address');
        $table->integer('housenumber');
        $table->string('postalcode');
        $table->string('city');
        $table->string('province');
        $table->string('email');
        $table->string('phonenumber');
        $table->timestamps();
    });

CreateUserCompanyPivotTable.php

    Schema::create('user_company', function (Blueprint $table) {
        $table->engine = "InnoDB";
        $table->integer('user_id')->unsigned();
        $table->integer('company_id')->unsigned();
    });

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

错误：

Illuminate\Database\QueryException  : SQLSTATE[HY000]: General error: 1215 

Cannot add foreign key constraint (SQL: alter table `user_company` add constraint `user_company_user_id_foreign` foreign key (`user_id`) references `users` (`id`) on delete cascade)

Answer 1

迁移失败，因为 user_company 中 user_id 的数据类型与 users 中的 id 不匹配。

您在 users table 中使用了 bigIncrement()，它创建了一个类型为 UNSIGNED BIGINT 的 auto_increment 字段。

在 user_company table 中，您使用 integer()->unsigned() 创建 user_id，这会创建一个 auto_increment 字段，类型为 UNSIGNED INT。

MySQL 创建外键时需要两个字段类型相同。

要解决此问题，您应该用 bigInteger()->unsigned() 创建 user_id。

Schema::create('user_company', function (Blueprint $table) {
    $table->engine = "InnoDB";
    $table->bigInteger('user_id')->unsigned();
    $table->bigInteger('company_id')->unsigned();
    // You don't need separate schema code to create foreign
    $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
    $table->foreign('company_id')->references('id')->on('companies')->onDelete('cascade');
});

Laravel 迁移添加外键给出错误外键 (`user_id`)

Laravel migration add foreign key gives error foreign key (`user_id`)

database-migration

laravel-5