php - PHP遍历数组以从数据库中获取每个键的值(第三种形式)

我正在建立一个系统，主要是巩固学习，但将用于实践。
我将试着口头解释我所关注的E-R图的部分：
每个学员可以有许多统一格式的
每个Uniform ID都是表Uniform中的一个新条目，因此cadets（table）可能看起来像：

id | name    | ... | uniformID

1  | Example | ... | 1,2,3

uniform表格：

id | notes             | cadet

1  | Need new blahh    | 1

2  | Some stuff needed | 1

3  | Whatever you like | 1

仔细想想，看起来我不需要数据库中的第三列。
我试图在uniformID中遍历每个id，代码：

<?php
$cadet = $_GET['id']; // set  from URL

$query = mysql_query("SELECT `uniformID` FROM `cadets`
  WHERE id = '$cadet' LIMIT 1")
  or die(mysql_error()); // get uniform needed as string

// store it
while ($row = mysql_fetch_array($query)) {
  $uniformArray = $row['uniformID'];
}
echo $uniformArray . "  ";
$exploded = explode(",", $uniformArray); // convert into an array

// for each key in the array perform a new query
foreach ($exploded as $key => $value) {
  $query(count($exploded));
  $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'");
}

?>
正如我所说，这主要是为了进行整合，但我发现了一个错误，sql说：
致命错误：函数名必须是第82行C:\ wamp\www\intranet\uniform.php中的字符串
第82行是：

$query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'");

我不确定它能不能用，所以我试了一下，现在卡住了！
编辑：
感谢所有为此做出贡献的人！这就是工作代码：

foreach ($exploded as $key => $value) {
              //$query(count($exploded));
              $query = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'");
              while ($row = mysql_fetch_array($query)) {
                echo "<tr>
                  <td>" . $row['id'] . "</td>
                  <td>" . $row['note'] . "</td>
                </tr>";
              }
            }

添加while并通过在foreach中嵌套它来执行迭代

最佳答案

除了你的桌子

cadets(id, ...)
uniforms(id, ...)

使用描述cadets实体和uniforms实体之间关系的交叉乘积表

cadets_x_uniforms(cadet_id, uniform_id)

对于每个关系（在本例中，cadet x具有统一的y），将一个具有相应id的记录放入cross-product表中。
... 嗯，我想在这种情况下一个有效的例子会更好。。。

<?php
$pdo = new PDO('mysql:host=localhost;dbname=test;charset=utf8', 'localonly', 'localonly');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
setup($pdo);

// fetch the uniforms of a specific cadet
$stmt = $pdo->prepare('
    SELECT
        c.name,u.id,u.labelid
    FROM
        so_cadets as c
    LEFT JOIN
        so_cadet_uniform as cxu
    ON
        c.id=cxu.cadet_id
    LEFT JOIN
        so_uniforms as u
    ON
        cxu.uniform_id=u.id
    WHERE
        c.name=?
');
$stmt->execute( array('cadetB') );
$stmt->setFetchMode(PDO::FETCH_ASSOC);
echo "uniforms of cadetB\n";
foreach( $stmt as $row ){
    echo join(', ', $row), "\n";
}

// fetch cadets without uniforms
$query = '
    SELECT
        c.name
    FROM
        so_cadets as c
    WHERE
        NOT EXISTS(SELECT uniform_id FROM so_cadet_uniform as cxu WHERE c.id=cxu.cadet_id)
';
echo "cadets without uniforms\n";
foreach( $pdo->query($query, PDO::FETCH_ASSOC) as $row ){
    echo join(', ', $row), "\n";
}


function setup($pdo) {
    $pdo->exec('
        CREATE TEMPORARY TABLE so_cadets (
            id int auto_increment,
            name varchar(32),
            primary key(id)
        )
    ');

    $pdo->exec('
        CREATE TEMPORARY TABLE so_uniforms (
            id int auto_increment,
            labelid varchar(32),
            primary key(id),
            unique key(labelid)
        )
    ');

    $pdo->exec('
        CREATE TEMPORARY TABLE so_cadet_uniform (
            cadet_id int,
            uniform_id int,
            primary key(cadet_id,uniform_id)
        )
    ');


    $stmt = $pdo->prepare('INSERT INTO so_cadets (name) VALUES (?)');
    foreach( range('A','F') as $c ) {
        $stmt->execute( array('cadet'.$c));
    }

    $stmt = $pdo->prepare('INSERT INTO so_uniforms (labelid) VALUES (?)');
    foreach( range('K','Z') as $c ) {
        $stmt->execute( array('label'.$c));
    }

    $stmt = $pdo->prepare('INSERT INTO so_cadet_uniform (cadet_id,uniform_id) VALUES (?,?)');
    $cadetHasUniforms = array(
        1=>array(1,2,3), // <- cadetA
        2=>array(7,9), // <- cadetB
        3=>array(8,5,4), // <- cadetC
        // 4=>array() <- cadetD, no entry, no uniforms
        5=>array(10,13,15) // <- cadetE
        // <- cadetE, no entry, no uniforms
    );
    foreach( $cadetHasUniforms as $cadetId=>$uniformIds ) {
        foreach( $uniformIds as $uid ) {
            $stmt->execute(array($cadetId, $uid));
        }
    }

}

印刷品

uniforms of cadetB
cadetB, 7, labelQ
cadetB, 9, labelS
cadets without uniforms
cadetD
cadetF

关于php - PHP遍历数组以从数据库中获取每个键的值(第三种形式)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13286991/