Php 在foreach循环中正确使用foreach循环

我的数据库中有以下数据：

initial   |    word
---------------------------
   E      |    Example1
   E      |    Example2
   N      |    Nextexample1

所需输出：

E
Example1
Example2

N
Nextexample1

E
Example1

E
Example2

N
Nextexample1

<?php
    $pdo = new PDO('mysql:host=...');           
    $sql = "SELECT DISTINCT initial, word FROM `exampletable` ORDER by initial ASC";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    if($stmtrecords = $stmt->fetchall(PDO::FETCH_ASSOC))
    {

    foreach($stmtrecords as $result)
    {
?>

<div>
    <?php echo $result['initial'];?>
</div>
<br>
<div>
    <?php echo $result['word'];?>
</div>
<br><br>

因此，对于每个首字母，它应该显示该首字母以及以该首字母开头的所有单词。对我来说很重要：每个单词都应该显示在一个单独的分区中，这样就不会有

分组（

单词

分隔符'，'））

建议了

此时的输出：

E
Example1
Example2

N
Nextexample1

E
Example1

E
Example2

N
Nextexample1

<?php
    $pdo = new PDO('mysql:host=...');           
    $sql = "SELECT DISTINCT initial, word FROM `exampletable` ORDER by initial ASC";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    if($stmtrecords = $stmt->fetchall(PDO::FETCH_ASSOC))
    {

    foreach($stmtrecords as $result)
    {
?>

<div>
    <?php echo $result['initial'];?>
</div>
<br>
<div>
    <?php echo $result['word'];?>
</div>
<br><br>

此时我的代码：

E
Example1
Example2

N
Nextexample1

E
Example1

E
Example2

N
Nextexample1

<?php
    $pdo = new PDO('mysql:host=...');           
    $sql = "SELECT DISTINCT initial, word FROM `exampletable` ORDER by initial ASC";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    if($stmtrecords = $stmt->fetchall(PDO::FETCH_ASSOC))
    {

    foreach($stmtrecords as $result)
    {
?>

<div>
    <?php echo $result['initial'];?>
</div>
<br>
<div>
    <?php echo $result['word'];?>
</div>
<br><br>

问题：

E
Example1
Example2

N
Nextexample1

E
Example1

E
Example2

N
Nextexample1

<?php
    $pdo = new PDO('mysql:host=...');           
    $sql = "SELECT DISTINCT initial, word FROM `exampletable` ORDER by initial ASC";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    if($stmtrecords = $stmt->fetchall(PDO::FETCH_ASSOC))
    {

    foreach($stmtrecords as $result)
    {
?>

<div>
    <?php echo $result['initial'];?>
</div>
<br>
<div>
    <?php echo $result['word'];?>
</div>
<br><br>

---

显然，我需要一个额外的循环来解决这个问题，但我不知道如何确切地做到这一点？

我将使用

group\u concat

作为

<?php
    $pdo = new PDO('mysql:host=...');           
    $sql = "SELECT initial, group_concat(word) as word FROM `exampletable` group by initial ORDER by initial ASC";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    if($stmtrecords = $stmt->fetchall(PDO::FETCH_ASSOC))
    {

    foreach($stmtrecords as $result)
    {
       $words = $result['words'];
       $words_array = array();
       if(strlen($words) > 1) {
         $words_array = explode(',',$words);
       }
?>

<div>
    <?php echo $result['initial'];?>
</div>
<br>
<div>
    <?php
     if (count($words_array) > 0 ){
       foreach($words_array as $val){
         echo $val.'<br />';
       }
     }
    ?>
    <?php echo $result['word'];?>
</div>

实际上不需要额外的循环，只需要在循环中增加一点逻辑。由于查询按

initial

对数据进行排序，因此只需检查

$result['initial']

何时在循环中发生更改，并仅在此时输出标题

$initial = null;

foreach ($stmtrecords as $result) {
    if ($result['initial'] !== $initial) {
        $initial = $result['initial'];
        // output header div
    }
    // output word
}

请注意：在上面的代码中，您正在将数据库中的数据直接嵌入HTML。在插入HTML之前，应先转义该数据。有关如何正确转义数据的更多信息，请参阅和