从列中获取值，但返回null？

Question

我试图从我的数据库中的列回合中获得“回合”的值。所以，我想要获得每个辩论/帖子的一个字段值。基于价值/数量，它应该显示不同的东西。当我认为它的值为NULL时，即使该辩论/帖子的db字段中的值是4.这不仅仅是辩论，而是所有这些都会发生。如何获得列中字段的实际值并将其分配给名为$ rounds的变量。这个变量需要具有每次辩论的价值，而不仅仅是辩论。

<?php 
$servername = ""; 
$username = ""; 
$password = ""; 
$dbname = ""; 

$con = new mysqli($servername, $username, $password, $dbname); 

if($con->connect_error) 
{ 
    die("Connection failed: " . $con->connect_error); 
} 
else 
{ 
    $sql = "SELECT rounds FROM vf_Discussion"; 
    $result = $con->query($sql); 

    $allRounds = $result->fetch_row(); 
    $rounds = $allRounds[0]; 

    var_dump($rounds); 
} 

mysqli_close($con); 

$rounds1 = '<h2 class="CommentHeading">Round 1 (Pro)</h2> <br> <h2 class="CommentHeading">Round 1 (Con) </h2>'; 
$rounds2 = '<h2 class="CommentHeading">Round 2 (Pro)</h2> <br> <h2 class="CommentHeading">Round 2 (Con)</h2>'; 
$rounds3 = '<h2 class="CommentHeading">Round 3 (Pro)</h2> <br> <h2 class="CommentHeading">Round 3 (Con)</h2>'; 
$rounds4 = '<h2 class="CommentHeading">Round 4 (Pro)</h2> <br> <h2 class="CommentHeading">Round 4 (Con)</h2>'; 
$rounds5 = '<h2 class="CommentHeading">Round 5 (Pro)</h2> <br> <h2 class="CommentHeading">Round 5 (Con)</h2>'; 

foreach($allRounds as $rounds) 
{ 
    if($rounds == 1) 
    { 
    echo $rounds1; 
    foreach($Sender->Data('Answers') as $Row) 
    { 
     $Sender->EventArguments['Comment'] = $Row; 
     WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
    } 
    if($rounds == 2) 
    { 
    echo $rounds1; 
    echo $rounds2; 
    foreach($Sender->Data('Answers') as $Row) 
    { 
     $Sender->EventArguments['Comment'] = $Row; 
     WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
    } 
    if($rounds == 3) 
    { 
    echo $rounds1; 
    echo $rounds2; 
    echo $rounds3; 
    foreach($Sender->Data('Answers') as $Row) 
    { 
     $Sender->EventArguments['Comment'] = $Row; 
     WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
    } 
    if($rounds == 4) 
    { 
    echo $rounds1; 
    echo $rounds2; 
    echo $rounds3; 
    echo $rounds4; 
    foreach($Sender->Data('Answers') as $Row) 
    { 
     $Sender->EventArguments['Comment'] = $Row; 
     WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
    } 
    if($rounds == 5) 
    { 
    echo $rounds1; 
    echo $rounds2; 
    echo $rounds3; 
    echo $rounds4; 
    echo $rounds5; 
    foreach($Sender->Data('Answers') as $Row) 
    { 
     $Sender->EventArguments['Comment'] = $Row; 
     WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
    } 
} 
?> 

Answer 1

我用PDO s。您的错误是在$rounds的转让。 而且我清理了代码以获得更好的可读性：

<?php 
$servername = ""; 
$dbname = ""; 
$username = ""; 
$password = ""; 

$pdo = NULL; 

try 
{ 
    $pdo = new PDO('mysql:host=' . $servername . ';dbname=' . $dbname, $username, $password); 
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
} 
catch(PDOException $exception) 
{ 
    die("Connection failed: " . $exception->getMessage()); 
} 

$rounds = []; // array we want to save all the rounds to 

// the database 
$query = "SELECT rounds, COUNT(*) AS cnt FROM vf_Discussion GROUP BY rounds ORDER BY rounds"; 
$statement = $pdo->prepare($query); 
$statement->execute(); 

$rows = $statement->fetchAll(\PDO::FETCH_ASSOC); 

foreach($rows as $row) 
{ 
    $rounds[] = ['name' => $row['rounds'], 'count' => $row['cnt']]; 
} 

foreach($rounds as $round) 
{ 
    $name = $round['name']; 
    $cnt = $round['cnt']; 

    echo '<h2 class="CommentHeading">Round ' . $round . ' (Pro)</h2> <br> <h2 class="CommentHeading">Round ' . $round . ' (Con)</h2> <br> <h2 class="CommentHeading">Number of Rounds ' . $cnt . '</h2>'; 

    foreach($Sender->Data('Answers') as $Row) 
    { 
    $Sender->EventArguments['Comment'] = $Row; 
    WriteComment($Row, $Sender, Gdn::Session(), 0); 
    } 
} 
?>