Question

我是PHP新手，想知道你是否可以帮助我选择总和查询？

我想根据user_id在我的数据库中添加费用表中的总金额？

这是我到目前为止所拥有的

<?php
    //sets up thisPage          
    $pageSize=10;
    if (isset($_POST["thisPage"])) 
        $thisPage = $_POST["thisPage"];
    else 
        $thisPage=1;

    //selects all distinct expenses that have been uploaded
    $dbQuery="SELECT SUM(amount) AS TotalExpenditure FROM expenses WHERE user_id =       '$userID'; ";

    echo $dbQuery;

    $dbResult=mysqli_query($db_connection, $dbQuery) or die (mysqli_error($db_connection));

    echo "<table> <thead>";
    //echo '<tr> <th>Project ID</th><th>Project Name</th></tr> </thead>';
    while ($dbRow=mysqli_fetch_array($dbResult)){
        // display row with expense
        echo '<tr> <td>'. $dbRow['amount'] .'</td>';
    }
    echo "</table>";
    echo "</form>";

?>

Answer 1

你有

$dbRow['amount']

但你使用

SUM(amount) AS TotalExpenditure
             // ^ this is the name (alias) of your column now

TotalExpenditure是金额的名称，因此最后一部分应为

echo '<tr> <td>'. $dbRow['TotalExpenditure'] .'</td> </tr>';

Answer 2

您必须使用TotalExpenditure作为数组的键，所以

$dbRow['TotalExpenditure']代替$dbRow['TotalExpenditure']？

你给count() sql函数添加了一个别名，所以你必须使用它

PHP使用SELECT SUM

2 个答案: