mysql - 我如何从3张 table 中获得值(value)？

表：项目
enter image description here

表格：projects_departments enter image description here
表：部门enter image description here

这是模型项目

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

这是模型Project_department

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);
}

这是我的刀片

project->departments->department_name

这是我的错误
SQLSTATE [42S22]：找不到列：1054“ where子句”中的未知列“ projects_departments.project_id”（SQL：从projects_departments中选择*，其中projects_departments。project_id = 48和projects_departments。project_id是不为空）

最佳答案

$project = DB::table('projects')
        ->select(*)
        ->join('Department', 'projects_departments.department_id', '=', 'Department.id')
        ->join('projects_departments', 'projects_departments.project_id', '=', 'projects.id')

        ->get();

让我们试试这个

关于mysql - 我如何从3张 table 中获得值(value)？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53185383/