dongmingxiang0312
dongmingxiang0312
2013-02-12 13:56
浏览 33
已采纳

PHP PDO MySQL查询打印空白

Going through a PHP MySQL tutorial and switching the PHP out for PDO; at any rate, my query is coming up blank.

$get_cat = $that->dbh->query("SELECT `cat_name`, `cat_desc` FROM `categories`");

            if(isset($get_cat))
            {
        while($row = $get_cat->fetch(PDO::FETCH_ASSOC))
            {
                printf("
                <tr>
                    <td>".$row['cat_name']." : ".$row['cat_desc']."</td>
                </tr>
                ");
            }
            }
            else
                {
                    echo '<tr><td>return is false</td></tr>';
                }    

$That refers to:

include('db.php');
$that = new lib();    

OLD: So, why is my query blank? Before putting the die in it would return Boolean and give in an error in the loop with the die in it just comes up blank. The categories table has data in it and the page is refreshed on submission for new entries. NEW: Fatal error: Call to a member function fetch() on a non-object in C:\wamp\www\forum\create_category.php on line 36

Line 36 is the while loop line.

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3条回答 默认 最新

  • douzhuangna6906
    douzhuangna6906 2013-02-12 14:41
    已采纳

    You need to tell PDO to throw errors.

    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $res = $that->dbh->query("SELECT cat_name, cat_desc FROM categories");
    while($row = $res->fetch())
    {
        echo "<tr><td>$row[cat_name] : $row[cat_desc]</td></tr>
    ";
    }
    

    run your code, read the error message and take appropriate action

    Don't forget to add the first line into your db.php file, to make the setting permanent

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  • doufuhao0566
    doufuhao0566 2013-02-12 13:59

    mysql_fetch_array is not PDO. You would need something like:

    while($row = $get_cat->fetch(PDO::FETCH_ASSOC))
    

    To get your rows.

    Nor can you use mysql_error() to get the error. You could use for example $that->dbh->errorInfo() but you should look into exceptions for a more robust way to catch all errors.

    Edit: You should check what the error is. Using isset is pointless as you have just assigned a value to it, so it will always be set.

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  • dongqiao8417
    dongqiao8417 2013-02-12 13:59

    Your query is incorrect -- is this what you're trying to do?

    SELECT `categories`.`cat_name`, `categories`.`cat_desc` FROM `categories`
    

    Hard to know without seeing you table structure.

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