php - 选择插槽最大的行

Question

我需要选择 slot_left 最大的一行。我试过了

for ( $i=1;$i<3;$i++) {
    $sql5 = "SELECT * from user u where (
        select max(slot_left) from company c,user u 
        where c.id=u.company_id and c.id='$name'
    )";
    $result5 = mysqli_query($link, $sql5) or die(mysqli_error($link));
    while($row=mysqli_fetch_array($result5)) {  
        // echo the id which the slot_left is the biggest      
        echo $i['slot_left'];
    }
}

但还是不行。请帮忙!

Answer 1

您必须在查询中使用 GROUP BY。并且不推荐在 Loop 中执行查询，它会降低性能。

试试这个。

$sql5 = "select c.id, max(slot_left) from company c,user u 
        where c.id=u.company_id and c.id='$id' GROUP by c.id";

    $result5 = mysqli_query($link, $sql5) or die(mysqli_error($link));
    while($row=mysqli_fetch_array($result5)) {  
        echo $row['slot_left'];
    }