Question

我希望将结果显示在表格列的下拉列表中，仅显示所选位置和尚未分配的其他可用位置。

表从中选择结果：

TITLE     | LINK        | POSITION  |
-------------------------------------
Home      | home.php    |   1       |
-------------------------------------
Contact   | contact.php |   2       |
-------------------------------------
about     | about.php   |   3       |
-------------------------------------

所有职位

(1,2,3,4,5,6)

带下拉框的页面

/* extract data from table*/ 

if(isset($_GET['edit_id']))
{
$id = $_GET['edit_id'];
extract($update->getID('pages','TITLE',$id));
}

/* dropdown with results*/

<label class="control-label" for="basicinput">POSITION</label>
<select name="POSITION" class="span8" id="POSITION" tabindex="1">
<?php 
$view->menu_drop($POSITION)  
?>
</select>

功能过滤下拉框

 <?php
 public function menu_drop($value)
{
$stmt = $this->db->prepare("SELECT POSITION FROM pages");
$stmt->execute();
while ($row=$stmt->fetch(PDO::FETCH_ASSOC)) {
$catg=$row["POSITION "];
if( $value == $catg )
{
echo "<option selected = 'selected' value=\"$catg\">$catg</option>"; 
} else
{ 
/* i am lost here. I would like to display the other available positions excluding the positions already assigned pages in the table*/
}
}   
}
?>

Answer 1

简单的机制是使用三元测试，以便每次循环while循环时将变量设置为selected或nothing

同样，类方法应该被封装并且不会影响它们自身。使方法构建一个包含html的字符串，而不是从方法中回显它，然后，理论上，如果你愿意，你可以修改它的结果。

<?php
public function menu_drop($value)
{
    $htm = '';

    $stmt = $this->db->prepare("SELECT POSITION FROM pages");
    $stmt->execute();
    while ($row=$stmt->fetch(PDO::FETCH_ASSOC)) {

        $sel = $value == $row['POSITION'] ? "selected='selected'" : '';
        $htm .= "<option $sel value='{$row['POSITION']}'>{$row['POSITION']}</option>"; 
    }
    return $htm;
}
?>

然后将您的通话流程更改为

/* dropdown with results*/

<label class="control-label" for="basicinput">POSITION</label>
<select name="POSITION" class="span8" id="POSITION" tabindex="1">
<?php 
    echo $view->menu_drop($POSITION);
?>
</select>

Answer 2

试试这个

public function menu_drop ($value) {
    echo "<option value=\"0\">Remove Position</option>";
    for ($i= 1; $i <=6; $i++) {
        $found = false;
        $stmt = $this->db->prepare("SELECT POSITION FROM pages");
        $stmt->execute();
        while ($row=$stmt->fetch(PDO::FETCH_ASSOC)) {
            $catg=$row["POSITION"];
            if ($catg == $i && $i != $value) {
                $found = true;
            }
        }
        if (!$found) {
            if ($value == $i) {
                echo "<option selected = 'selected' value=\"$i\">$i</option>";  
            } else { 
                echo "<option value=\"$i\">$i</option>";
            }
        }
    }
}

PHP显示结果显示一个下拉列表，不包括已选择的值

2 个答案: