Javascript 三分之一下拉列表使用mysql创建冲突
好的，以下是我的表格：Javascript 三分之一下拉列表使用mysql创建冲突,javascript,php,mysql,select,foreign-keys,Javascript,Php,Mysql,Select,Foreign Keys,好的，以下是我的表格： departments associates +--------+------------------+--------------+ +---------+------------------+-----------+------------+ | dep_id | dep_name | date_added | | asso_id | ass
departments associates
+--------+------------------+--------------+ +---------+------------------+-----------+------------+
| dep_id | dep_name | date_added | | asso_id | asso_name | dep_id | date_added |
+--------+------------------+--------------+ +---------+------------------+-----------+------------+
| 1 | Pick a Department| Date | | 1 | A Associate | 2 | Date |
| 2 | Department A | Date | | 2 | B Associate | 3 | Date |
| 3 | Department B | Date | | 3 | C Associate | 4 | Date |
| 4 | Department C | Date | | 4 | D Associate | 5 | Date |
| 5 | Department D | Date | | 5 | A Associate 2 | 2 | Date |
+--------+------------------+--------------+ +---------+------------------+-----------+------------+
key_list key_log
+--------+------------+--------------+ +------+--------------+------------+-------------+----------------+
| key_id | key_name | date_added | | id | key_assigned | key_status | assigned_to | assigned_by |
+--------+------------+--------------+ +------+--------------+------------+-------------+----------------+
| 1 | Key 1 | Date | | 1 | Key 1 | 0 | A Associate | logged in name |
| 2 | Key 2 | Date | | 2 | Key 4 | 0 | B Associate | logged in name |
| 3 | Key 3 | Date | | | | | | |
| 4 | Key 4 | Date | | | | | | |
| 5 | Key 5 | Date | | | | | | |
+--------+------------+--------------+ +------+--------------+------------+-------------+----------------+
因此，经过一些研究后，我这样做：
<?php
$dbhost_name = "localhost";
$database = "db_name";
$username = "user_name";
$password = "password";
try {
$dbo = new PDO('mysql:host='.$dbhost_name.';dbname='.$database, $username, $password);
} catch (PDOException $e) {
print "Error!: " . $e->getMessage() . "<br/>";
die();
}
?>
<!DOCTYPE html>
<html>
<head>
<script>
function reload(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value;
self.location='dd.php?cat=' + val ;
}
</script>
</head>
<body>
<?Php
@$cat=$_GET['cat']; // Use this line or below line if register_global is off
if(strlen($cat) > 0 and !is_numeric($cat)){ // to check if $cat is numeric data or not.
echo "Data Error";
exit;
}
$quer3="SELECT DISTINCT key_name, key_id FROM key_iv order by key_name";
$quer2="SELECT DISTINCT category,cat_id FROM category order by category";
if(isset($cat) and strlen($cat) > 0){
$quer="SELECT DISTINCT subcategory FROM subcategory where cat_id=$cat order by subcategory";
}else{$quer="SELECT DISTINCT subcategory FROM subcategory order by subcategory"; }
echo "<form method=post name=f1 action='dd-check.php'>";
// Starting of first drop down
echo "<select name=key_names><option value=''>Select Key</option>"; // list box select command
foreach ($dbo->query($quer3) as $row){//Array or records stored in $row
echo "<option value=$row[id]>$row[key_name]</option>";
/* Option values are added by looping through the array */
}
echo "</select>";// Closing of list box
echo "<select name='cat' onchange=\"reload(this.form)\"><option value=''>Select one</option>";
foreach ($dbo->query($quer2) as $noticia2) {
if($noticia2['cat_id']==@$cat){echo "<option selected value='$noticia2[cat_id]'>$noticia2[category]</option>"."<BR>";}
else{echo "<option value='$noticia2[cat_id]'>$noticia2[category]</option>";}
}
echo "</select>";
// This will end the first drop down list
// Starting of second drop downlist
echo "<select name='subcat'><option value=''>Select one</option>";
foreach ($dbo->query($quer) as $noticia) {
echo "<option value='$noticia[subcategory]'>$noticia[subcategory]</option>";
}
echo "</select>";
// This will end the second drop down list
echo "<input type=submit value=Submit>";
echo "</form>";
?>
</body>
</html>
函数重载（表单）
{
var val=form.cat.options[form.cat.options.selectedIndex].value；
self.location='dd.php？cat='+val；
}
我认为您第二次尝试的问题是，您从查询中获取了key\u name和key\u id，但在其中，您在引用key\u name和id（而不是key\u id）的选项中写出了值：
卡洛斯，您可能想尽快更改密码，因为您不小心将其粘贴在了第二个示例的顶部：）您可能也应该选择一个更安全的密码。创建易于记忆且相当安全的密码。谢谢@JonKloske，我一定会这么做，谢谢你的网站。我不太担心这个问题，因为我正在本地系统上使用mamp进行测试。我很抱歉响应太晚，Jon，我正在研究printf vs echo，我正在研究htmlentities以及何时使用它们。我已经利用了你的答案，它是有效的。当我把下拉列表放在开头时，我也明白了为什么我的第二种方法会出现问题。不知何故，我的查询$db有一个额外的字母，所以它不是$db而是$dbo，这引起了很多混乱。无论如何，我的下一个任务是创建一个条目，以便在每次向员工注销密钥时存储信息，并检查密钥是否已注销。谢谢。不用担心，希望上面的内容有更广泛的帮助，即使最初的问题是打字错误！：）如果你不关心历史记录，简单地拥有一个可空的“checkedOutBy”字段可能是最简单的方法。如果您确实关心历史记录，则可以使用另一个表，其中包含keyid、checkedoutby、checkoutdate和checkindate。要检查某个键是否可用，请确保该键在第二个表中没有checkindate为null的条目（您可以使用左连接、按keyid分组和SUM（chekindate为null）作为未完成项，且未完成项=0。
<?php
$db = new mysqli('localhost', 'carlos', 'Security5', 'testing');
$query = "SELECT dep_id, dep_name FROM department";
$result = $db->query($query);
while($row = $result->fetch_assoc()){
$categories[] = array("id" => $row['dep_id'], "val" => $row['dep_name']);
}
$query = "SELECT ass_id, dep_id, ass_name FROM associates";
$result = $db->query($query);
while($row = $result->fetch_assoc()){
$subcats[$row['dep_id']][] = array("id" => $row['ass_id'], "val" => $row['ass_name']);
}
$jsonCats = json_encode($categories);
$jsonSubCats = json_encode($subcats);
?>
<!docytpe html>
<html>
<head>
<script type='text/javascript'>
<?php
echo "var categories = $jsonCats; \n";
echo "var subcats = $jsonSubCats; \n";
?>
function loadCategories(){
var select = document.getElementById("categoriesSelect");
select.onchange = updateSubCats;
for(var i = 0; i < categories.length; i++){
select.options[i] = new Option(categories[i].val,categories[i].id);
}
}
function updateSubCats(){
var catSelect = this;
var catid = this.value;
var subcatSelect = document.getElementById("subcatsSelect");
subcatSelect.options.length = 0; //delete all options if any present
for(var i = 0; i < subcats[catid].length; i++){
subcatSelect.options[i] = new Option(subcats[catid][i].val,subcats[catid][i].id);
}
}
</script>
</head>
<body onload='loadCategories()'>
<?php
$quer3="SELECT DISTINCT key_name, key_id FROM key_list order by key_name";
echo "<select name=key_names><option value=''>Select Key</option>"; // list box select command
foreach ($dbo->query($quer3) as $row){//Array or records stored in $row
echo "<option value=$row[id]>$row[key_name]</option>";
/* Option values are added by looping through the array */
}
echo "</select>";// Closing of list box
?>
<select id='categoriesSelect'>
</select>
<select id='subcatsSelect'>
</select>
</body>
</html>
<?php
$quer3="SELECT DISTINCT key_name, key_id FROM key_list order by key_name";
echo "<select name=key_names><option value=''>Select Key</option>"; // list box select command
foreach ($dbo->query($quer3) as $row){//Array or records stored in $row
echo "<option value=$row[id]>$row[key_name]</option>";
/* Option values are added by looping through the array */
}
echo "</select>";// Closing of list box
?>
<?php
$querykeys = "SELECT DISTINCT key_name, key_id FROM key_list order by key_name";
printf("<select name='key_names'>\n");
printf("<option value=''>Select Key</option>\n");
foreach ($dbo->query($querykeys) as $row) {
printf("<option value='%s'>%s</option>",
htmlentities($row['key_id'], ENT_QUOTES),
htmlentities($row['key_name'], ENT_QUOTES)
);
}
echo "</select>\n";
?>