下面是我创建下拉列表的代码，我能够从MySQL中检索数据，但我必须为每个字段重复选项步骤，如何为下拉列表设置代码，以便我可以缩短在选择列表中调用它一次，就像在for循环中一样。另外，如果没有选择，以及从数据库中存储的列表中选择数据，如何创建要显示的错误消息
<form action="sign.php" method="post">
<label for="employee_name">Employee name</label>
<select name = "employee_name">
<option value=""> -----------Select----------- </option>
<?php
$stmt = $pdo->prepare('Select name from people');
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
echo '<option>'.$row['name'].'</option>';
}
?>
</select>
<label for="manager">manager</label>
<select name = "manager">
<option value=""> -----------Select----------- </option>
<?php
$stmt = $pdo->prepare('Select name from people');
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
echo '<option>'.$row['name'].'</option>';
}
?>
</select>
<label for="senior">Senior</label>
<select name = "Senior">
<option value=""> -----------Select----------- </option>
<?php
$stmt = $pdo->prepare('Select name from people');
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
echo '<option>'.$row['name'].'</option>';
}
?>
</select>
<input type="submit" name="register" value=" Click to Add"></button>
</form>
使用数组并运行一次查询来设置数组中的选项。
<?php
$optionArray = array();
$stmt = $pdo->prepare('Select name from people');
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$optionArray[] = '<option value="'.$row['name'].'">'.$row['name'].'</option>';
}
?>
<form action="sign.php" method="post">
<label for="employee_name">Employee name</label>
<select name = "employee_name">
<option value=""> -----------Select----------- </option>
<?php
foreach($optionArray as $row)
{
echo $row;
}
?>
</select>
如何为下拉列表设置代码，以便我可以缩短在选择列表中调用它一次，就像在 for 循环中一样。
只需创建一个循环。 虽然它应该是foreach，而不是for。
首先收集您的数据，
$people = $pdo->query('Select name from people order by name')->fetchAll(PDO::FETCH_COLUMN);
$sections = [
'employee_name' => 'Employee name',
'manager' => 'Manager',
'senior' => 'Senior',
];
然后循环它
<form action="sign.php" method="post">
<?php foreach ($sections as $label => $caption): ?>
<label for="<?=$label?>"><?=$caption?></label>
<select name = "<?=$label?>">
<option value=""> -----------Select----------- </option>
<?php foreach ($people as $name): ?>
<option><?=$name?></option>
<?php endforeach ?>
</select>
<?php endforeach ?>
<input type="submit" name="register" value=" Click to Add"></button>
</form>
而不是每次都重复此操作，您可以创建一个执行相同任务的方法。
<label for="employee_name">Employee name</label>
<select name = "employee_name">
<option value=""> -----------Select----------- </option>
<?=loadOptions('name','people');?> <!--shortcut way to echo in php-->
</select>
<?php
function loadOptions($field,$table){
$stmt = $pdo->prepare('Select '.$field.' from '.$table);
$stmt->execute();
$options='';
while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$options .= '<option>'.$row['name'].'</option>';
}
return $options;
}
?>