Question

我想按用户ID

计算值列

例如：我想计算标记列中id = 1的值意味着（30 + 70 + 30）在获取sql代码中的用户标记后如何做到这一点

数据库示例

id         mark       user_id
-----      ----       -------- 
1          30         1
2          60         3
3          70         1
4          10         2
5          30         1

我的代码

<?php 

$mark = $DB_con->prepare("SELECT id,mark,user_id FROM `tablename` WHER user_id=".$userRow['id']."");
$mark->execute();
foreach($mark->fetchAll() as $mar){
     echo count($mar['mark']);  
}

?>

Answer 1

为什么不喜欢

$mark = $DB_con->prepare("
SELECT sum(mark) 
FROM   `tablename` 
WHERE  user_id = ?");
$mark->bindParam(1, $userrow['id'], PDO::PARAM_INT);

顺便说一下，如果你从客户端获取那个用户ID，你可能应该使用bindParam，这样你就不会受到sql注入的攻击。</ p>

Answer 2

也许是这样的事情;

<?php 

$mark = $DB_con->prepare("SELECT id, mark, user_id FROM `tablename` WHERE user_id=$userRow['id']");
$mark->execute();
$total = 0;
foreach($mark->fetchAll() as $mar){
     $total += $mar['mark'];  
}
echo $total;

?>

Answer 3

<?php 

$mark = $DB_con->prepare("SELECT id,mark,user_id FROM `tablename` WHER     user_id=".$userRow['id']."");
 $mark->execute();
 $counter = 0; // <-- THIS -----------
 foreach($mark->fetchAll() as $mar){
     echo count($mar['mark']); 
     $counter += $mar['mark']; // <-- THIS ----------

 }

echo $counter;

?>

*还错过了＆＃39; WHERE＆＃39;在上面的陈述中。

php计数值列

3 个答案: