PHP中的ISSET檢查不起作用

Question

我有這個PHP代碼。 當我嘗試不提交而手動導航到此php腳本時，未顯示未設置帖子的錯誤。 我究竟做錯了什么？

<?php
if (!isset($_POST['submit']));
 {
    $productname=$_POST['productname'];
    //$conn string will go here 
    $result=$conn->query("INSERT INTO products(pname)VALUES('$productname')");
    if($result)
    {
       echo "<font color=\"green\">";
       echo("Successfully Inserted new Products");
       echo"</font>!";
    }
    else
     {
       echo("error");
     }
}
?>

Answer 1

<?php
// semicolon removed
if (isset($_POST['submit'])) {
    $productname=$_POST['productname'];
    //$conn string will go here 
    $result=$conn->query("INSERT INTO products(pname)VALUES('$productname')");
    if($result) {
        echo "<font color=\"green\">";
        echo("Successfully Inserted new Products");
        echo"</font>!";
    }
} else { // else placed correctly ...
    echo("error");
}
?>

Answer 2

通過縮進，我們可以看到您的else條件位於“ if (!isset($_POST['submit'])) ”內。另外，我認為在if (!isset($_POST['submit']))

<?php
if (!isset($_POST['submit'])); // <== This semicolon shouldn't exist
{
    $productname=$_POST['productname'];
    //$conn string will go here 
    $result=$conn->query("INSERT INTO products(pname)VALUES('$productname')");
    if($result)
    {
        echo "<font color=\"green\">";
        echo("Successfully Inserted new Products");
        echo"</font>!";
    }
    else
    {
        echo("error");
    }
} // <== Need an "else" here
?>

這是應該的代碼

<?php
if (isset($_POST['submit']))
{
    $productname=$_POST['productname'];
    //$conn string will go here 
    $result=$conn->query("INSERT INTO products(pname)VALUES('$productname')");
    if($result)
    {
        echo "<font color=\"green\">";
        echo("Successfully Inserted new Products");
        echo"</font>!";
    }
    else
    {
        echo "<font color=\"red\">";
        echo("Error when inserting");
        echo"</font>!";
    }
} 
else
{
    echo "error";
}
?>

編輯：

您需要執行“ if (isset($_POST['submit'])) ”而不是“ if (!isset($_POST['submit'])) ”來測試表單是否已提交。 我修復了上面的代碼。