PHP脚本优化：实现数据库行条件式处理与即时跳过机制

<?php

// 假设 $connection 已经建立了数据库连接
// 假设 $criteria 是一个布尔表达式，用于判断行是否符合条件

$finished = false; // 标志位，指示是否已找到符合条件的行

while (!$finished) {
    // 1. 从数据库获取第一行数据
    // 每次循环都会重新执行 SELECT LIMIT 1，因为前一行已被删除
    $q = mysqli_query($connection, "SELECT * FROM table_name LIMIT 1");
    if (!$q) {
        // 错误处理：查询失败
        error_log("Database query failed: " . mysqli_error($connection));
        break; // 退出循环
    }
    $row = mysqli_fetch_assoc($q);

    if (!$row) {
        // 数据库中已无数据可处理，退出循环
        echo "No more rows to process in the database.\n";
        $finished = true;
        continue;
    }

    // 2. 在此处定义并评估你的业务条件
    // 示例：$row MEETS CRITERIA;
    // 这是一个占位符，你需要根据实际业务逻辑来替换
    $finished = ($row['some_column'] > 100); // 假设的条件

    // 3. 删除当前处理的行
    // 无论行是否符合条件，都将其删除，以便下一次循环能获取到新的“第一行”
    $id_to_delete = $row['id']; // 假设 'id' 是主键
    $delete_q = mysqli_query($connection, "DELETE FROM table_name WHERE id = '$id_to_delete'");
    if (!$delete_q) {
        // 错误处理：删除失败
        error_log("Failed to delete row with ID: $id_to_delete. Error: " . mysqli_error($connection));
        // 可以选择退出循环或继续，取决于业务需求
        // break;
    }

    if (!$finished) {
        echo "Row ID {$id_to_delete} did not meet criteria. Checking next row...\n";
    }
}

if ($finished) {
    echo "Successfully found and processed a row that met the criteria.\n";
} else {
    echo "Loop terminated without finding a suitable row (or due to an error).\n";
}

?>

<?php

$finished = false;
$retries = 5; // 设置最大重试次数

while (!$finished && $retries-- > 0) { // 注意 $retries-- > 0 的用法
    // 1. 从数据库获取第一行数据
    $q = mysqli_query($connection, "SELECT * FROM table_name LIMIT 1");
    if (!$q) {
        error_log("Database query failed: " . mysqli_error($connection));
        break;
    }
    $row = mysqli_fetch_assoc($q);

    if (!$row) {
        echo "No more rows to process. Remaining retries: " . ($retries + 1) . "\n";
        $finished = true; // 数据库为空，视为完成处理
        continue;
    }

    // 2. 评估业务条件
    // 示例：从外部API获取数据并进行比较
    $e = $row['id'];
    $asin_queue = $row['asin'];
    $price_queue = $row['new_price'];

    // 模拟外部API调用，获取新价格
    // 实际应用中需要处理API调用失败的情况
    $api_keepa = 'YOUR_KEEPA_API_KEY'; // 替换为你的API Key
    $r = @file_get_contents("https://api.keepa.com/product?asin=$asin_queue&key=$api_keepa");
    if ($r === FALSE) {
        error_log("Failed to fetch data from Keepa API for ASIN: $asin_queue");
        // 考虑是否将此行标记为失败或跳过，不计入重试
        // 如果API调用失败，可以不删除当前行，让其在下次重试时再次被处理
        // 或者直接 break 退出循环
        // break;
        continue; // 跳过当前行，继续下一次循环（会减少重试次数）
    }

    $gz = gzdecode($r);
    $t = json_decode($gz);
    $new_price = $t->products[0]->csv; // 假设获取到的价格路径

    // 3. 更新或执行其他业务逻辑
    // ...

    // 4. 评估是否符合条件
    $finished = ($new_price <= $price_queue); // 假设条件是新价格低于或等于队列价格

    // 5. 删除当前处理的行
    $delete_q = mysqli_query($connection, "DELETE FROM table_name WHERE id = '$e'");
    if (!$delete_q) {
        error_log("Failed to delete row with ID: $e. Error: " . mysqli_error($connection));
        // 此时可能需要更复杂的错误处理，例如记录失败的ID，或重试删除
    }

    if (!$finished) {
        echo "Row ID {$e} (ASIN: {$asin_queue}) did not meet criteria. Retries left: {$retries}. Checking next row...\n";
    }
}

if ($finished) {
    echo "Loop finished: A suitable row was found and processed, or no more rows.\n";
} else {
    echo "Loop finished: No suitable row found within {$retries} retries, or an error occurred.\n";
}

?>