使用 php 和 mysql 计算总值而不是行

Question

我正在尝试计算收集的令牌总数，而不是mysql数据库中的记录数。虽然我已经将SUM函数放在查询中，但它仍然计算no。行数。<?php    $conn = mysqli_connect(server, dbuser, dbpw, db);   $query = " SELECT SUM(nooftokensused) FROM bidding WHERE biddedon >= DATE_FORMAT(CURRENT_DATE(), '%Y-01-01') GROUP BY biddingid";   $query_run = mysqli_query($conn, $query);   $row = mysqli_num_rows($query_run);    echo '<h1>'.$row.'</h1>';?>

Answer 1

我已经在我的代码中添加了注释。此外，您正在使用 ，您尚未将它们声明为带有符号的变量。mysqli_connect(server, dbuser, dbpw, db)$

<?php

    //Make connection with DB

    $con = mysqli_connect($server, $dbuser, $dbpw, $db);

    if (mysqli_connect_errno()) {

      echo "Failed to connect to MySQL: " . mysqli_connect_error();

      exit();

    }

    $sql = "SELECT SUM(nooftokensused) as summ FROM bidding WHERE biddedon >= DATE_FORMAT(CURRENT_DATE(), '%Y-01-01') GROUP BY biddingid";

    $result = mysqli_query($con, $sql);

    if(mysqli_num_rows($result)>0)

    {

        // Associative array

        $row = mysqli_fetch_assoc($result);

        echo $row["summ"];

    }

    else

    {

        echo 0;

    }

    // Free result set

    mysqli_free_result($result);

    mysqli_close($con);

    ?>

Answer 2

使用 mysqli_fetch_assoc（） 而不是 mysqli_num_rows（）。

<?php 

                $conn = mysqli_connect(server, dbuser, dbpw, db);

                $query = " SELECT SUM(value_sum) AS nooftokensused FROM bidding WHERE biddedon >= DATE_FORMAT(CURRENT_DATE(), '%Y-01-01') GROUP BY biddingid";

                $query_run = mysqli_query($conn, $query);

                $row = mysqli_fetch_assoc($query_run); 

                echo '<h1>'.$row['nooftokensused'].'</h1>';

 ?>