如何用一个查询显示多个表

Question

我正在尝试显示几个表，其中的特定元素只能使用单个数据库查询列出。我正在使用 IF 来调节特定元素的显示以分隔信息。但是我不能，我不知道语法是否不正确或者是否可以这样做。

<?php
    require_once('const.php');
    $conn = mysqli_connect(DBHOSTNAME,DBUSERNAME,DBPASSWORD,DBDATABASE) or exit('Error:'.mysqli_connect_error());
    mysqli_set_charset($conn,'utf8');
    $query = 'SELECT product.nome AS nome, category.name AS category, product.value
        FROM product INNER JOIN category ON product.category_id=category.id';
    $res = mysqli_query($conn,$query) or exit('Error:'.mysqli_error($conn));
    ?>
    <table>
        <tr>
            <th colspan="4"><p>Plates</p></th>
        </tr>
        <?php
        if(isset mysqli_query($query['category']) == ("Plates")){

        while($row = mysqli_fetch_assoc($res)) {
            ?>
            
            <tr>
                <td></td>
                <td><?php echo $row['name']; ?></td>
                <td><?php echo $row['value']; ?></td>
                <td></td>
            </tr>
            <?php
        }
    }
        mysqli_free_result($res);
        mysqli_close($conn);
        ?>
    </table>

Answer 1

哦，我想我现在明白了。您想查询数据库一次，但在页面的多个位置使用部分结果集。

因此运行查询并将结果集放入一个数组中，您可以根据需要一次又一次地使用该数组。

<?php
    require_once('const.php');
    $conn = mysqli_connect(DBHOSTNAME,DBUSERNAME,DBPASSWORD,DBDATABASE);
    mysqli_set_charset($conn,'utf8');

    $query = 'SELECT product.nome AS nome, category.name AS category, product.value
              FROM product 
                    INNER JOIN category ON product.category_id=category.id';

    $res = mysqli_query($conn,$query);
    $all_results = [];  // init the array
    while ( $row = $res->fetch_assoc() ) {
        $all_results[] = $row;
    }

    #some drives allow fetch_all() so you could replace above while loop with
    #$all_results = $res->fetch_all();   // get all the results one call

    ?>
    <table>
        <tr>
            <th colspan="4"><p>Plates</p></th>
        </tr>
    <?php
    // using the array, pick only the Plates category rows for this sction of the page
    foreach ( $all_results as $row ) {
        if ( $row['category']) == "Plates" ){

    ?>
        <tr>
            <td></td>
            <td><?php echo $row['nome']; ?></td>
            <td><?php echo $row['value']; ?></td>
            <td></td>
        </tr>
    <?php
        }
    }
    ?>
    </table>

如何用一个查询显示多个表

How to show several tables with a single query

php

mysqli