Zend Framework 子查询选择。违反基数：操作数应包含 1 列

Question

这是我的查询：

$subquery = "(SELECT `id`, `mark`, `date`, `session` FROM `student_marks` WHERE `student_id` = '" . $studentId . "')";

    $q = $this->select()
        ->distinct()
        ->setIntegrityCheck(false)
        ->from($this->_name, array('name AS subjectName', 'student_marks' => new Zend_Db_Expr($subquery)))
        ->joinLeft('class_teachers', 'class_teachers.subject_id = subjects.id', '')
        ->joinLeft('teachers', 'teachers.id = class_teachers.teacher_id', array('teachers.name AS teacherName', 'teachers.family AS teacherFamily'))
        ->joinLeft('student_session_marks', 'student_session_marks.subject_id = subjects.id', array('student_session_marks.id AS sessionMarkId', 'student_session_marks.mark AS sessionMarkName', 'student_session_marks.session AS sessionMarkSession'))
        ->where('student_session_marks.student_id = ?', $studentId);

查询打印：

SELECT DISTINCT `subjects`.`name` AS `subjectName`, 
    (SELECT `id`, `mark`, `date`, `session` FROM `student_marks` WHERE `student_id` = '6') AS `student_marks`, 
    `teachers`.`name` AS `teacherName`, `teachers`.`family` AS `teacherFamily`, `student_session_marks`.`id` AS `sessionMarkId`, 
    `student_session_marks`.`mark` AS `sessionMarkName`, `student_session_marks`.`session` AS `sessionMarkSession` 
FROM `subjects`
LEFT JOIN `class_teachers` ON class_teachers.subject_id = subjects.id
LEFT JOIN `teachers` ON teachers.id = class_teachers.teacher_id
LEFT JOIN `student_session_marks` ON student_session_marks.subject_id = subjects.id 
WHERE (student_session_marks.student_id = '6')

当我删除子查询时，我的查询成功，否则有这个错误：

SQLSTATE[21000]: Cardinality violation: 1241 Operand should contain 1 column(s).

Answer 1

这是操作符错误...当您对选择进行内部查询时，它必须只返回 1 列和 1 条记录，而不是多行/多列数据集。

与任何任务一样，解决任务的方法很少，要获得最佳解决方案，需要清楚地了解您要做什么......

根据您的代码，我认为以下是您正在寻找的内容：

public function getStudentSubjectMarks($studentId)
{
    // cast your input (assume it's numeric...
    $studentId = (int) $studentId;

    //
    $db = $this->getAdapter();
    $q = $db->select()
            ->distinct()
            ->from($this->_name, array('name AS subjectName'))
            ->joinLeft('class_teachers', 'class_teachers.subject_id = subjects.id')
            ->joinLeft('teachers', 'teachers.id = class_teachers.teacher_id', array(
                'teachers.name AS teacherName',
                'teachers.family AS teacherFamily',
            ))
            ->joinLeft('student_session_marks', 'student_session_marks.subject_id = subjects.id', array(
                'student_session_marks.id AS sessionMarkId',
                'student_session_marks.mark AS sessionMarkName',
                'student_session_marks.session AS sessionMarkSession'
            ))
            ->where('student_session_marks.student_id = ?', $studentId);

    $data = array();
    foreach ($db->fetchAll($q) as $record) {
        $queryMarks = $db->select()
                ->from('student_marks', array('id', 'mark', 'date', 'session'))
                ->where('student_id = ?', $studentId);

        //  add marks to the student record
        $record['student_marks'] = $db->fetchAll($queryMarks);

        //  add to main return array
        $data[] = $record;
    }

    // more logic...

    return $data;        
}