Question

我使用laravel框架。我写了这个查询，但显示出一个错误：

错误：

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'schools.grade' in 'field list' (SQL: select `students`.`name`, `students`.`lastname`, students.id, max(`schools.grade`) as `grade` from `students` inner join `schools` on `schools`.`id` = `students`.`id` group by `schools`.`id` having `grade` = 6)

我的代码：

$stu = students::join('schools', 'schools.id',"=", 'students.id')
            ->select('students.name','students.lastname',DB::raw('students.id, max(`schools.grade`) as `grade`'))
            ->groupBy('schools.id')
            ->having('grade','=',$grade)
            ->get();
        dd($stu);

怎么了？

Answer 1

$stu = students::join('schools as s', 's.id',"=", 'students.id')
            ->select('students.name','students.lastname','students.id, 
               DB::raw(max(`s.grade`) as `grade`')) // make sure grade exist in school? if in student then use students.grade in db:Row
            ->groupBy('s.id')
            ->having('grade','=',$grade)
            ->get();

Answer 2

你这样写。...

   $stu = students::join('schools', 'schools.id',"=", 'students.id')
        ->select('students.name','students.lastname',DB::raw('students.id,max(`schools.grade`) as `grade`'))
        ->groupBy('schools.id')
        ->having('schools.grade','=',$grade)->get();
    dd($stu);

Answer 3

第一件事是您要验证grade表中是否有列schools，因为这很可能就是问题所在。

如果您起诉它确实存在，那么也尝试在having条件下使用表名：

$stu = students::join('schools', 'schools.id',"=", 'students.id')
            ->select('students.name','students.lastname',DB::raw('students.id, max(`schools.grade`) as `grade`'))
            ->groupBy('schools.id')
            ->having('schools.grade','=',$grade)
            ->get();
dd($stu);

Answer 4

在这里

$stu = students::join('schools', 'schools.id',"=", 'students.id')
            ->select('students.name','students.lastname',DB::raw('students.id, max(`schools.grade`) as `grade`'))
            ->groupBy('schools.id')
            ->having('schools.grade','=',$grade)  // please chnage your code here..
            ->get();

Answer 5

我检查了这两个查询作为测试，它们分别工作。但是主查询（我首先提到）可能无法正常工作。

DB::table('schools')
         ->select(DB::raw('id, max(`grade`) as `grade`'))
          ->groupBy('id')
          ->having('grade','=',$grade)
         ->get();

和：

$stu = students::join('schools', 'schools.id',"=", 'students.id')
         ->select('students.name','students.lastname','students.id','schools.grade')
           ->where('schools.grade','=',$grade)  
           ->get();

laravel：错误：使用联接，原始和在查询中

5 个答案: