使用PDO的PHP代码不会将数据插入到DB表中

Question

我将插入表单的数据插入到数据库表中。这里使用POST方法通知我将数据发送到PDO的后台功能。表单是前端Bootstrap表单，PDO是后端。但是代码无效，请帮帮我。

表单代码： 这是Form表的Bootstrap代码，它是前端。

<div class="col-lg-6">
                        <div class="card alert">
                            <div class="card-header">
                                <h4>Horizontal Form</h4>                                   
                            </div>
                            <div class="card-body">
                                <div class="horizontal-form">
                                    <form method="post" action="channel.php" class="form-horizontal">
                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Name</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="name" type="text" class="form-control" placeholder="Channel Name" required>
                                            </div>
                                        </div>
                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Description</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="desp" type="text" class="form-control" placeholder="Channel Description" required>
                                            </div>
                                        </div>

                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Field 1</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="f1" type="text" class="form-control" placeholder="Field 1" required>
                                            </div>
                                        </div>

                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Field 2</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="f2" type="text" class="form-control" placeholder="Field 2">
                                            </div>
                                        </div>

                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Field 3</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="f3" type="text" class="form-control" placeholder="Field 3">
                                            </div>
                                        </div>

                                        <div class="form-group">
                                            <label class="col-sm-2 control-label">Field 4</label>
                                            <div class="col-sm-10">
                                                <input style="color:white" name="f4" type="text" class="form-control" placeholder="Field 4">
                                            </div>
                                        </div>
                                        <div class="form-group">
                                            <div class="col-sm-offset-2 col-sm-10">
                                                <button type="submit" class="btn btn-default">Create Channel</button>
                                            </div>
                                        </div>
                                    </form>
                                </div>
                            </div>
                        </div>
                    </div>

PDO功能

public function create_channel($name,$desp,$f1,$f2,$f3,$f4)
{
    try {
        $db = DB();
        $query = $db->prepare("INSERT INTO sensor_table(table_name, table_desp, field_1, field_2, field_3, field_4) VALUES (:name,:desp,:fl1,:fl2,:fl3,:fl4)");
        $query->bindParam("name", $name, PDO::PARAM_STR);
        $query->bindParam("desp", $desp, PDO::PARAM_STR);
        $query->bindParam("fl1", $f1, PDO::PARAM_STR);
        $query->bindParam("fl2", $f2, PDO::PARAM_STR);
        $query->bindParam("fl3", $f3, PDO::PARAM_STR);
        $query->bindParam("fl4", $f4, PDO::PARAM_STR);
        $query->execute()
        return $db->lastInsertId();     
    } catch (PDOException $e) {
        header("Location: login.php");
        exit($e->getMessage());
    }
}

数据库连接代码：

define('HOST', 'localhost'); 
define('USER', 'root'); 
define('PASSWORD', ''); 
define('DATABASE', 'elg_iot');

function DB()
{
 try {
     $db = new PDO('mysql:host='.HOST.';dbname='.DATABASE.'', USER,  PASSWORD);
    return $db;
 } catch (PDOException $e) {
    return "Error!: " . $e->getMessage();
    die();
 }
}