小编tEc*_*nUt的帖子

我收到下面列出的以下错误,并想知道如何解决此问题.

Not unique table/alias: 'grades'

这是我认为给我问题的代码.

function getRating(){
$dbc = mysqli_connect ("localhost", "root", "", "sitename");

$page = '3';

$sql1 = "SELECT COUNT(*) 
         FROM articles_grades 
         WHERE users_articles_id = '$page'";

$result = mysqli_query($dbc,$sql1);

if (!mysqli_query($dbc, $sql1)) {
        print mysqli_error($dbc);
        return;
}

$total_ratings = mysqli_fetch_array($result);

$sql2 = "SELECT COUNT(*) 
         FROM grades 
         JOIN grades ON grades.id = articles_grades.grade_id
         WHERE articles_grades.users_articles_id = '$page'";

$result = mysqli_query($dbc,$sql2);

if (!mysqli_query($dbc, $sql2)) {
        print mysqli_error($dbc);
        return;
}

$total_rating_points = mysqli_fetch_array($result);
if(!empty($total_rating_points) && !empty($total_ratings)){
// set the width of …

可能重复:
mysql_fetch_array()期望参数1是资源,在select中给出boolean

我收到下面列出的以下警告,我想知道如何解决它

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given on line 65

代码围绕下面列出的PHP代码部分.如果需要,我可以列出完整的代码.

// function to retrieve average and votes
function getRatingText(){
    $dbc = mysqli_connect ("localhost", "root", "", "sitename");
    $sql1 = "SELECT COUNT(*) 
             FROM articles_grades 
             WHERE users_articles_id = '$page'";

    $result = mysqli_query($dbc,$sql1);
    $total_ratings = mysqli_fetch_array($result);

    $sql2 = "SELECT COUNT(*) 
             FROM grades 
             JOIN grades ON grades.id = articles_grades.grade_id
             WHERE articles_grades.users_articles_id = '$page'";

    $result = mysqli_query($dbc,$sql2);
    $total_rating_points = mysqli_fetch_array($result);
    if (!empty($total_rating_points) && !empty($total_ratings)){
        $avg = (round($total_rating_points / $total_ratings,1)); …

我继续收到以下错误,我想知道如何解决它.

Fatal error: Unsupported operand types on line 97

它围绕下面列出的代码区域.如果需要,我可以列出完整的代码.

PHP代码

$total_rating_points = mysqli_fetch_array($result);
if (!empty($total_rating_points) && !empty($total_ratings)){
    $avg = (round($total_rating_points / $total_ratings,1));
    $votes = $total_ratings;
    echo $avg . "/10  (" . $votes . " votes cast)";
} else {
    echo '(no votes cast)';
}

这是第97行

$avg = (round($total_rating_points / $total_ratings,1));

这是完整的代码.

function getRatingText(){
    $dbc = mysqli_connect ("localhost", "root", "", "sitename");

    $page = '3';

    $sql1 = "SELECT COUNT(*) 
             FROM articles_grades 
             WHERE users_articles_id = '$page'";

    $result = mysqli_query($dbc,$sql1);

    if (!mysqli_query($dbc, $sql1)) …