Error Help: Warning: mysql_num_rows() expects para

问题:

I'm building a simple PHP CRUD app and I'm running into this error:

Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in

<?php 
$query = "select * from user";
$result = mysql_query($query);

if (mysql_num_rows($result) > 1) {
    echo "<table align='center' border='1'>";
    echo "<tr>";
    echo "<th>Id</th>";
    echo "<th>Username</th>";
    echo "<th>Password</th>";
    echo "</tr>";
    while($row = mysql_fetch_array($result)) {
        echo "<tr>";
        echo "<td>".$row['id']."</td>"; 
        echo "<td>".$row['username']."</td>";   
        echo "<td>".$row['password']."</td>";
        echo "<td><a href='index.php?operation=edit&id=".$row['id']."&username=".$row['username']."&password=".$row['password']."'>edit</a></td>";
        echo "<td><a href='index.php?operation=delete&id=".$row['id']."'>delete</a></td>";  
        echo "</tr>";
    }
    echo "</table>";
} else {
    echo "<center>No Records Found!</center>";  
}
?>

The error points to the 34th line in that code. Any help would be greatly appreciated!

回答1:

Usually this means your query failed due to incorrect fieldnames etc - are you sure your table exists? Try using some error handling to give an idea what the issue is.

$result = mysql_query($query) or die('Cannot Execute:'. mysql_error());