问题描述

可以绑定表名吗?

我想创建一个类来读取表中的列，并根据字段类型为我生成表单输入.当我执行 $form = new form("users"); 时，构造函数应该从使用以下代码从表中获取字段名称开始:

I want to make a class to read the columns from a tables and, depending on field type, generate the form inputs for me. When I do $form = new form("users");, the constructor is supposed to start with getting the field names from the table with the following code:

class form{

    public function __construct($table, $skip = array("id")){
        $pdo = new PDO('mysql:host=localhost;dbname=site;',USER,PASS);

        $query = $pdo->prepare("DESCRIBE :table");

        $query->bindValue(':table', $table, PDO::PARAM_STR, strlen($table));

        $query->execute();

        while($field = $query->fetch(PDO::FETCH_NUM)){
            var_dump($field);
            echo "<br /><br />";
        }

        unset($pdo);
    }
}

当我在准备语句中指定users"而不是:table"时，这工作得很好，但是绑定它正在工作，我很确定这是因为它试图绑定一个表名.此外，这需要绑定，因为我希望能够通过 $_GET 等传递我的表名.

This works just fine when I specify "users" instead of ":table" in the prepare statement, but the bind it's working, and I'm pretty sure it's because it's trying to bind a table name. Also, this needs to be binded because I'd like to have the ability to pass my table names through $_GET and the such.

推荐答案

可以绑定表名吗?

Is it possible to bind a table name?

没有

您必须将表名列入白名单.我怀疑您是否想让用户从您的数据库中浏览任何 表.

You have to whitelist table names. I doubt you want to let a user to browse any table from your database.

而且您还必须手动格式化标识符.有一个带有示例的 tag wiki.为什么不先读呢?

And you have to format identifiers manually as well. There is a tag wiki with example. Why not read it first?

更新:如您所见，PDO 对于现实生活中的任务来说并不方便.所以，你必须有一个更智能的抽象库来处理 MySQL 查询.下面是一个使用 safeMysql 类的示例，它可以显着缩短您的代码:

Update: As you can see, PDO turns out to be inconvenient for real life tasks. So, you have to have a more intelligent abstraction library to handle MySQL queries. Here is an example using the safeMysql class, which will make your code dramatically shorter:

class form{
    public function __construct($table){
        global $db;
        return $db->getAll("DESCRIBE ?n", $table);
    }
}

2 条注释:

• 我删除了第二个参数，因为您的函数中没有使用它的代码.
• 永远不要在课堂上联系.请改用已打开的连接.或者你会用这么多连接杀死你的 MySQL 服务器.

排除已实现的版本

class form {
    public function __construct($table,$skip = array("id")){
        global $db;
        $data = array();
        $res = $db->query("DESCRIBE ?n", $table);
        while($row = $db->fetch($res)) {
            if (!in_array($row['Field'],$skip)) {
                $data[] = $row;
            }
        }
        return $data;
    }
}

然而，这样的类很少可以按预期使用 - 总是有很多例外和手动格式化才能使其可用.

However, such class seldom can be used as intended - there are always a lot of exceptions and manual formatting to make it usable.

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