错误的原因可能是什么？

Question

I'm writing code to fetch data from the database but it keeps on flagging the error:

Notice: Undefined variable: word in C:\\xampp\\htdocs\\Zubby\\admin\\updateword.php on line 7

<?php 

if(isset($_POST['submit']))
    $word = $_POST['word'];

    include '../include/config.php' ;
    $sql = "SELECT FROM word WHERE word = $word";

    $fetch = mysqli_query($connect, $sql);
    if ($fetch) {
        echo $word;
    }else{
        echo "No such word exists in the database";
    }

?>

<form name="word-Add" method="POST" action="">
    <input type="text" name="word" placeholder="  Type the Word "><br><br><br><br>
    <input type="submit" name="submit" id="submit" value="Search Word"><br><br><br><br>

</form>

Answer 1

Try

<?php 

if(isset($_POST['submit']))
{
    $word = $_POST['word'];

    include '../include/config.php' ;
    $sql = "SELECT * FROM word WHERE word = '".$word."'";

    $fetch = mysqli_query($connect, $sql);
    if ($fetch) {
        echo $word;
    }else{
        echo "No such word exists in the database";
    }
}

?>

<form name="word-Add" method="POST" action="">
    <input type="text" name="word" placeholder="  Type the Word "><br><br><br><br>
    <input type="submit" name="submit" id="submit" value="Search Word"><br><br><br><br>

</form>

Please note though that your code is highly insecure! Never use user input directly in a query! Better use prepared statements: http://php.net/manual/en/pdo.prepared-statements.php