表：项目在此处输入图像描述
表：项目\此处为部门图像描述表：此处为部门图像描述
这是样板工程

public function projects_departments() {
    return $this->hasMany(Project_department::class); 
}

这是模型项目部

public function projects()
{
    return $this->belongsTo(Project::class);
}

public function departments()
{
    return $this->belongsTo(Department::class);
}

这是模特部

public function projects()
{
    return $this->hasMany(Project::class);
}

public function projects_departments() {
    return $this->hasMany(Project_department::class); 
}

这是我的刀

project->departments->department_name

这是我的错误sqlstate[42s22]：找不到列：“where子句”中的1054未知列“projects\u departments.project\u id”（sql:select*from） projects_departments 哪里 projects_departments . project_id =48和 projects_departments . project_id （不为空）