Question

我是PHP MySqli的新手，这是我的第一个项目。我试图通过放置在数组中从函数返回值。

function riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to){
    global $connection;
    $sql = "SELECT ".$id."  FROM ".$datatable." WHERE ".$id1." BETWEEN '".$date_from."' AND '".$date_to."' AND ".$id." = '".$type."'";

    if ($result = mysqli_query($connection,$sql)) {
        $count = 0;
        while ($row = mysqli_fetch_array($result)) {
            $count = ++ $count; 
        }
        echo "<br>".$type.": " .  $count;
        $counter[$type] = $count;
        return $counter;      
    }

    $type = 'RIDDOR - Major Injury';
    riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to);
    var_dump($counter);

该函数工作到可以打印结果的程度，该结果基本上是数组的各种计数。但是，我需要在其他表中使用return，但是var-dump只会返回NULL。

Answer 1

就像上面的所有注释一样，您正在使用$counter就像它是全局变量一样-如果是这种情况，则可以在函数开头添加global $counter，否则要用作返回值值，可以将其添加到函数参数中。

选项1-使用全局变量

function riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to){
    global $connection;
    global $counter;
    $sql = "SELECT ".$id."  FROM ".$datatable." WHERE ".$id1." BETWEEN '".$date_from."' AND '".$date_to."' AND ".$id." = '".$type."'";

    if ($result = mysqli_query($connection,$sql)) {
        $count = mysqli_num_rows($result);
        echo "<br>".$type.": " .  $count;
        $counter[$type] = $count;     
    }
}

$type = 'RIDDOR - Major Injury';
riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to);
var_dump($counter);

选项2-使用返回值

function riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to){
    global $connection;
    $sql = "SELECT ".$id."  FROM ".$datatable." WHERE ".$id1." BETWEEN '".$date_from."' AND '".$date_to."' AND ".$id." = '".$type."'";

    if ($result = mysqli_query($connection,$sql)) {
        $count = mysqli_num_rows($result);
        echo "<br>".$type.": " .  $count;
        return $count;     
    }
}

$type = 'RIDDOR - Major Injury';
$counter[$type] = riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to);
var_dump($counter);

我强烈推荐第二个选项，以避免使用全局...

Answer 2

您的代码应如下所示。不用在php中计数，您可以在查询中计数。

function riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to){
    global $connection; global $counter;
    $sql = "SELECT COUNT(".$id.") as cnt FROM ".$datatable." WHERE ".$id1." BETWEEN '".$date_from."' AND '".$date_to."' AND ".$id." = '".$type."'";
    $count = 0;
    if($result = mysqli_query($connection,$sql)) {
       if ($row = mysqli_fetch_assoc($result)) {
            $count = $row['cnt']; 
        }  
    }
    $counter[$type] = $count;
}
$type = 'RIDDOR - Major Injury';
riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to);
var_dump($counter);

Answer 3

您似乎正在使用昂贵的方法。通过一些功能，您可以轻松获取查询行数。

function riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to){
global $connection;
$sql = "SELECT ".$id."  FROM ".$datatable." WHERE ".$id1." BETWEEN '".$date_from."' AND '".$date_to."' AND ".$id." = '".$type."'";
$result = mysqli_query($connection,$sql)

return mysqli_num_rows($result);
}

$type = 'RIDDOR - Major Injury';
$counter = riddor_dates($type,$id,$id1,$datatable,$date_from,$date_to);
var_dump($counter);

PHP在函数中返回数组

3 个答案: