php - 使用 PHP 从 SQL 中选择随机行，但从特定点到点 ID

Question

我正在制作某种测验项目，我想从数据库中选择并显示随机行，但仅限从 ID 5 到 ID 25 的行，以便显示 20 个问题并将状态从不显示更新为显示。

$stmt = $DB_con->prepare('SELECT * FROM questions_Library (no idea)');
$stmt->execute();

if($stmt->rowCount() > 0){
    while($row=$stmt->fetch(PDO::FETCH_ASSOC)){
        echo $row['question'];
    }
}

Database visualization

Answer 1

那么您应该将结果集限制为 20。

$stmt = $DB_con->prepare('SELECT * FROM questions_Library LIMIT 20');
$stmt->execute();

if($stmt->rowCount() > 0){
    while($row=$stmt->fetch(PDO::FETCH_ASSOC)){
        echo $row['question'];
    }
}

//Update the state of questions returned to displayed

您可能还想仅选择那些尚未显示的内容

$stmt = $DB_con->prepare('SELECT * FROM questions_Library WHERE displayed = 0 LIMIT 20');
$stmt->execute();

if($stmt->rowCount() > 0){
    while($row=$stmt->fetch(PDO::FETCH_ASSOC)){
        echo $row['question'];
    }
}

//Update the state of questions returned to displayed