如何合并学生分阶段成绩数据，实现同一科目成绩同行展示？

需要展示学生的**Prelim（期初）、Midterm（期中）、Finals（期末）**成绩，当前问题是同一科目的不同阶段成绩被拆分成多行显示，目标是让同一科目各阶段成绩在同一行展示。

现有代码 #

View 代码 #

<?php foreach($grades as $grade): ?>
<tr>
    <th scope="row"><?php echo $grade['subCode']; ?></th>
    <td><?php echo $grade['subject']; ?></td>
        <?php if($grade['gradePeriod']=="Prelim"): ?>
            <td><?php echo $grade['grade']; ?></td>
        <?php else: ?>
            <td>0</td>
        <?php endif; ?>

        <?php if($grade['gradePeriod']=="Midterm"): ?>
            <td><?php echo $grade['grade']; ?></td>
        <?php else: ?>
            <td>0</td>
        <?php endif; ?>

        <?php if($grade['gradePeriod']=="Finals"): ?>
            <td><?php echo $grade['grade']; ?></td>
        <?php else: ?>
            <td>0</td>
        <?php endif; ?>

    <td><?php echo $grade['remarks']; ?></td>
</tr>
<?php endforeach; ?>

Model 代码 #

public function gradePeriod(){
    $this->db->select('subCode,subject,grade,gradePeriod,remarks');
    $this->db->from('tbl_college_grades');
    $this->db->where('studentID', ' 200171419');
    $this->db->where('schoolYear','2022-2023');
    $this->db->where('semester','First Semester');
    $query = $this->db->get();
    return $query->result_array();
}

问题原因 #

当前数据库查询返回的每条记录对应单个科目+单个阶段的成绩，foreach循环时每个阶段都会生成一行，导致同一科目被拆分成多行显示。

解决方案 #

推荐在Model层重组数据（符合MVC架构，数据逻辑与视图分离），也可以在View层临时处理。

方案1：Model层重组数据 #

修改Model方法，将同一科目的不同阶段成绩合并到同一数组中：

public function gradePeriod(){
    $query = $this->db->select('subCode,subject,grade,gradePeriod,remarks')
                      ->from('tbl_college_grades')
                      ->where('studentID', '200171419')
                      ->where('schoolYear','2022-2023')
                      ->where('semester','First Semester')
                      ->get();
    
    $consolidatedGrades = [];
    foreach($query->result_array() as $row){
        $subCode = $row['subCode'];
        // 初始化科目结构（首次遇到该科目时）
        if(!isset($consolidatedGrades[$subCode])){
            $consolidatedGrades[$subCode] = [
                'subCode' => $row['subCode'],
                'subject' => $row['subject'],
                'prelim' => 0,
                'midterm' => 0,
                'finals' => 0,
                'remarks' => $row['remarks']
            ];
        }
        // 根据成绩阶段赋值
        switch(strtolower($row['gradePeriod'])){
            case 'prelim':
                $consolidatedGrades[$subCode]['prelim'] = $row['grade'];
                break;
            case 'midterm':
                $consolidatedGrades[$subCode]['midterm'] = $row['grade'];
                break;
            case 'finals':
                $consolidatedGrades[$subCode]['finals'] = $row['grade'];
                break;
        }
    }
    // 转换为索引数组，方便View遍历
    return array_values($consolidatedGrades);
}

对应的View代码简化为：

<?php foreach($grades as $grade): ?>
<tr>
    <th scope="row"><?php echo $grade['subCode']; ?></th>
    <td><?php echo $grade['subject']; ?></td>
    <td><?php echo $grade['prelim']; ?></td>
    <td><?php echo $grade['midterm']; ?></td>
    <td><?php echo $grade['finals']; ?></td>
    <td><?php echo $grade['remarks']; ?></td>
</tr>
<?php endforeach; ?>

方案2：View层临时处理（不推荐，仅作备选） #

如果无法修改Model，可在View层临时合并同一科目的数据：

<?php 
$currentSub = '';
$currentGrade = [
    'subCode' => '',
    'subject' => '',
    'prelim' => 0,
    'midterm' => 0,
    'finals' => 0,
    'remarks' => ''
];

foreach($grades as $grade):
    if($grade['subCode'] !== $currentSub){
        // 输出上一个科目的行（首次循环跳过）
        if($currentSub !== ''): ?>
            <tr>
                <th scope="row"><?php echo $currentGrade['subCode']; ?></th>
                <td><?php echo $currentGrade['subject']; ?></td>
                <td><?php echo $currentGrade['prelim']; ?></td>
                <td><?php echo $currentGrade['midterm']; ?></td>
                <td><?php echo $currentGrade['finals']; ?></td>
                <td><?php echo $currentGrade['remarks']; ?></td>
            </tr>
        <?php endif;
        // 初始化当前科目数据
        $currentSub = $grade['subCode'];
        $currentGrade = [
            'subCode' => $grade['subCode'],
            'subject' => $grade['subject'],
            'prelim' => 0,
            'midterm' => 0,
            'finals' => 0,
            'remarks' => $grade['remarks']
        ];
    }
    // 赋值对应阶段成绩
    match($grade['gradePeriod']){
        'Prelim' => $currentGrade['prelim'] = $grade['grade'],
        'Midterm' => $currentGrade['midterm'] = $grade['grade'],
        'Finals' => $currentGrade['finals'] = $grade['grade'],
    };
endforeach;
// 输出最后一个科目
if($currentSub !== ''): ?>
    <tr>
        <th scope="row"><?php echo $currentGrade['subCode']; ?></th>
        <td><?php echo $currentGrade['subject']; ?></td>
        <td><?php echo $currentGrade['prelim']; ?></td>
        <td><?php echo $currentGrade['midterm']; ?></td>
        <td><?php echo $currentGrade['finals']; ?></td>
        <td><?php echo $currentGrade['remarks']; ?></td>
    </tr>
<?php endif; ?>

内容的提问来源于stack exchange，提问作者Coder Codes