Question

我有一个PHP代码，可以在html表中添加/删除新行（tr）。一列（td）具有文本字段，第二列（td）具有下拉列表。下拉源是 mysql表。第一行（tr）值正确。但是当我添加新行（tr）时，dropdonwn list为null

代码是：

<html>
    <head>
        <title></title>
        <style type="text/css">
            input {
                display: block;   /* makes one <input> per line */
            }
        </style>
    </head>
    <?php
    include 'dbconnection\dbconnection.php'; // Database connection

    $count=1;
    if(isset($_POST['btnadd']) == "ADD NEW ITEM") {
        // add 1 to the row counter
        if (isset($_POST['count'])) $count = $_POST['count'] + 1;
        // set value for first load
        else $count = 1;
    }

    if(isset($_POST['btnremove']) == "DELTE ITEM") {
        // decrement the row counter
        $count = $_POST['count'] - 1;
        // set minimum row number
        if ($count < 1) $count = 1;
    }
    ?>
    <body>
        <!-- call same file on submit -->
        <form name="form1" method="POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">
            <?php 
            $cdquery="select cmc_id,cmc_name from cat_main_category";
            $result2=mysqli_query($conn,$cdquery) or die(mysqli_error());
            echo '<table>';
                // print $count rows
                for ($i=1; $i<=$count; $i++) {
                    echo ' <tr>  <td>     <input type="text" name="text'.$i.'" align="center">  </td>';
                    echo '<td> <select id="basicgroup'.$i.'" name="basicgroup'.$i.'" onchange=reload(this.form)>';
                    echo '<option value=0>Select</option>';

                    while ($row=mysqli_fetch_array($result2)) {
                        $cdTitle=$row["cmc_name"];
                        $id=$row["cmc_id"];
                        //if($id==@$basicgroup){
                        echo "<option selected value=$id>
                        $cdTitle
                        </option>";
                        /*}
                        else{echo "<option value=$id>
                        $cdTitle
                        </option>""."<BR>";;*/
                    }
                    echo '</select></td></tr>   ';      
                }      
                ?>
            </table>

            <!-- you only need one set of buttons and only one counter for this script
            because every button would do the same -->
            <input type="submit" name="btnadd" id="btnadd" value="ADD NEW ITEM" >
            <input type="submit" name="btnremove" id="btnremove" value="DELETE ITEM">
            <input type="hidden" name="count" value="<?php echo $count; ?>">
        </form>
    </body>
</html>

Answer 1

执行MySQL查询后： $ result2 = mysqli_query（$ conn，$ cdquery）或die（mysqli_error（））;

将结果保存在数组中，如：

$categories = [];
while ($row=mysqli_fetch_array($result2)) {
    $categories[$row["cmc_id"]] = $row["cmc_name"]
}

然后在你的主循环中：

for ($i=1; $i<=$count; $i++) {
    echo ' <tr>  <td>     <input type="text" name="text'.$i.'" align="center">  </td>';
    echo '<td> <select id="basicgroup'.$i.'" name="basicgroup'.$i.'" onchange=reload(this.form)>';
    echo '<option value=0>Select</option>';
    foreach ($categories as $id => $cdTitle) {
        echo "<option selected value=$id>
                $cdTitle
            </option>";
    }
    echo '</select></td></tr>';
}

您当前的问题是第一次迭代，您使用mysqli_fetch_array耗尽了MySQL查询，第二次选择为空

Answer 2

更改

body

要

<?php 
$cdquery="select cmc_id,cmc_name from cat_main_category";
$result2=mysqli_query($conn,$cdquery) or die(mysqli_error());
echo '<table>';
    for ($i=1; $i<=$count; $i++) {
        echo '<tr><td><input type="text" name="text'.$i.'" align="center"></td>';
        echo '<td><select id="basicgroup'.$i.'" name="basicgroup'.$i.'" onchange=reload(this.form)>';
        echo '<option value=0>Select</option>';
        while ($row=mysqli_fetch_array($result2)) {
            $cdTitle=$row["cmc_name"];
            $id=$row["cmc_id"];
            echo "<option selected value=$id>$cdTitle</option>";
        }
        echo '</select></td></tr>';      
    }      
    ?>
</table>

Put，

<?php 
echo '<table>';
    for ($i=1; $i<=$count; $i++) {
        $cdquery="select cmc_id,cmc_name from cat_main_category";
        $result2=mysqli_query($conn,$cdquery) or die(mysqli_error());
        echo '<tr><td><input type="text" name="text'.$i.'" align="center"></td>';
        echo '<td><select id="basicgroup'.$i.'" name="basicgroup'.$i.'" onchange=reload(this.form)>';
        echo '<option value=0>Select</option>';
        while ($row=mysqli_fetch_array($result2)) {
            $cdTitle=$row["cmc_name"];
            $id=$row["cmc_id"];
            echo "<option selected value=$id>$cdTitle</option>";
        }
        echo '</select></td></tr>';      
    }      
    ?>
</table>

在$cdquery="select cmc_id,cmc_name from cat_main_category"; $result2=mysqli_query($conn,$cdquery) or die(mysqli_error());圈内。

值没有出现在下拉列表中

2 个答案: