eloquent - 无法在 Laravel5.5 上添加外键约束

Question

我创建了几个表：

关键需求表：

public function up()
{
    Schema::create('keyneeds', function(Blueprint $table)
    {
        $table->integer('id', true);
        $table->integer('segment_id')->index('FK_KN_SEGMENT');
        $table->integer('design_id')->index('FK_KEYNEEDS_DESIGN');
        $table->integer('admin_id')->index('FK_KN_ADMIN');
        $table->string('kntextcolor', 191)->nullable();
        $table->string('kntextcolorhover', 191)->nullable();
        $table->string('knbgcolor', 191)->nullable();
        $table->string('knbgcolorhover', 191)->nullable();
        $table->string('knhvize', 191)->nullable();
        $table->timestamps();
        $table->softDeletes();
        $table->engine = 'InnoDB';
    });
}

设计表：

public function up()
{
    Schema::create('designs', function(Blueprint $table)
    {
        $table->integer('id', true);
        $table->string('design', 191)->nullable();
    });
}

我还添加了外键约束

public function up()
{
    Schema::table('keyneeds', function(Blueprint $table)
    {
        $table->foreign('design_id', 'FK_KEYNEEDS_DESIGN')->references('id')->on('designs')->onUpdate('RESTRICT')->onDelete('RESTRICT');
        $table->foreign('admin_id', 'FK_KN_ADMIN')->references('id')->on('admins')->onUpdate('RESTRICT')->onDelete('RESTRICT');
        $table->foreign('segment_id', 'FK_KN_SEGMENT')->references('id')->on('segments')->onUpdate('RESTRICT')->onDelete('RESTRICT');
    });
}

尝试迁移数据库时出现此 SQL 错误：

Can not add external index constraints (SQL: alter table `keyneeds` add constraint` FK_KEYNEEDS_DESIGN` foreign key (`design_id`) references`

igns (id`) 删除 RESTRICT 更新 RESTRICT)

标签： eloquentlaravel-5.5

Answer 1

Jonas Staudenmeir 给出了答案：

public function up()
{
    Schema::create('designs', function(Blueprint $table)
    {
        $table->integer('id', true);
        $table->string('design', 191)->nullable();
        $table->engine = 'InnoDB';
    });
}