当PHP下拉列表中有多个同名的选项时，如何只显示一个选项？

$options = array("选项1", "选项2", "选项2", "选项3", "选项4", "选项4");
$uniqueOptions = array_unique($options);

echo "<select>";
foreach ($uniqueOptions as $option) {
    echo "<option value='$option'>$option</option>";
}
echo "</select>";

// 假设数据库连接已经建立
$query = "SELECT DISTINCT option_value FROM options_table";
$result = mysqli_query($connection, $query);

echo "<select>";
while ($row = mysqli_fetch_assoc($result)) {
    $option = $row['option_value'];
    echo "<option value='$option'>$option</option>";
}
echo "</select>";