显示类中 SQL 的总 id 计数

Question

我正在使用三个文件相互连接：仪表板.php<?php  require_once('dashboard.vc.php');  echo $lstTotalCoupon['total_coupons'];?>仪表板.vc.php<?php  $routePath = "../";  require_once($routePath . "_config/db.php");    $dbConfig = new config_db();    $db = $dbConfig->init();  require_once($routePath . "_mc/Product.mc.php");  $mcProduct = new Product_MC();  $lstTotalCoupon = $mcProduct->SelectCountProduct($db);?>产品.mc.php<?phpClass Product_MC {   public function SelectCountProduct($db) {    $stmt = $db->prepare(" SELECT * AS total_coupons FROM product ");    $stmt->execute();    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);    return $rows;  }}?>我使用变量 $lstTotalCoupon 从 Product.mc.php 中获取选择计数，但出现错误注意：未定义索引：total_coupons。似乎缺少什么？

Answer 1

产品.mc.php

<?php

Class Product_MC {

   public function SelectCountProduct($db) {

    $stmt = $db->prepare(" SELECT * AS total_coupons FROM product ");

    $stmt->execute();

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

    return count($rows);

  }

}

?>

这将返回获取行的总数

或者你甚至可以这样设置：

<?php

Class Product_MC {

   public function SelectCountProduct($db) {

    $stmt = $db->prepare(" SELECT * AS total_coupons FROM product ");

    $stmt->execute();

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

    return $rows;

  }

}

?>

仪表板.vc.php

<?php

  $routePath = "../";

  require_once($routePath . "_config/db.php");

    $dbConfig = new config_db();

    $db = $dbConfig->init();

  require_once($routePath . "_mc/Product.mc.php");

  $mcProduct = new Product_MC();

  $lstTotalCoupon = $mcProduct->SelectCountProduct($db);

  $lstTotalCoupon['total_coupons'] = count($lstTotalCoupon);

?>

所以你会得到这样的：

echo $lstTotalCoupon['total_coupons'];

Answer 2

尝试返回SelectCountProduct()这样的：

<?php

Class Product_MC {

   public function SelectCountProduct($db) {

    $stmt = $db->prepare(" SELECT * FROM product ");

    $stmt->execute();

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

    $rows['total_coupons'] = $stmt->num_rows;

    return $rows;

  }

}

?>

Answer 3

修改您的查询以包含唯一 ID 的计数：

SELECT count(id) AS total_coupons FROM product

这将比大多数答案更有效，因为它是在数据库引擎中完成的。