Question

我的问题是：我的demo-results.php中的结果没有显示在demo.php中输入的数据中。数据存储在我的数据库中，但是javascript警告＆＃39; 0结果＆＃39;在demo.php页面将我重定向到demo-results.php页面后始终显示：

这是我的演示结果页面的php部分：

                      <div class="col-lg-12 text-center">
                            <hr class="visible-xs">
                            <h2>Water Reading is: </h2>
                            <hr class="visible-xs">

            <?php 
                    $servername = "localhost";
                    $username = "root";
                    $password = "";
                    $dbname = "water";

                    // Create connection
                    $conn = new mysqli($servername, $username, $password, $dbname);
                    // Check connection
                    if ($conn->connect_error) {
                        die("Connection failed: " . $conn->connect_error);
                    }

                    $sql = "SELECT first_number, second_number, third_number, fourth_number, fifth_number, sixth_number, prev_reading, pres_reading FROM demo_numbers ORDER BY post_id DESC LIMIT 1;";

                    $result = $conn->query($sql);

                    if ($result->num_rows > 2) {
                        // output data of each row
                        while($row = $result->fetch_assoc()) {

                ?>


                        <strong><?php echo $row["first_number"]. $row["second_number"] . $row["third_number"]. $row["fourth_number"] . $row["fifth_number"]. $row["sixth_number"] . "<br>";?></strong>

                            <hr class="visible-xs">
                            <h2>Your Water Usage is: </h2>
                            <hr class="visible-xs">
                            <strong>
                <?php 
                        $int_pres = intval($row["pres_reading"]);
                        $int_prev = intval($row["prev_reading"]); 
                        $difference = $int_pres-$int_prev;
                        $payment = $difference*26.678;      

                        echo $difference . " cu. m." . "<br>"; 

                        }
                ?></strong>  

                <hr class="visible-xs">
                            <h2>Your Payment is approximately: </h2>
                            <hr class="visible-xs">
                            <strong>
                <?php 


                         echo "Php " . $difference . "<br>"; ?></strong> 
                <?php
                    } else {
                        echo "<script>alert('0 results')</script>";
                    }

                    $conn->close();
                ?>

请帮我显示水阅读，用水和付款。谢谢。

Answer 1

您在查询中使用LIMIT：

SELECT first_number, second_number, third_number, fourth_number, fifth_number, sixth_number, prev_reading, pres_reading FROM demo_numbers ORDER BY post_id DESC LIMIT 1;

使用这个条件：

if ($result->num_rows > 2) {

您的查询只返回一条记录，因为您使用的是LIMIT 1，而此条件if ($result->num_rows > 2) {始终会失败。

<强>解决方案：

如果您想使用LIMIT 1，则可以使用条件：

if ($result->num_rows > 0) { // if no of rows found.

结果未在PHP中显示

1 个答案: