PHP MySQL 短查询关联代码

Question

我需要查询和关联许多这样的查询

<?php 
$datacenter=mysqli_connect('localhost','user','pass','db');

db 连接，现在我们计算选项 1 和 2 和 3 的投票数

 $r11=mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total1` 
FROM `votes` WHERE `firstvote` = '1' ");
    $r11r=mysqli_fetch_assoc($r11);


    $r12=mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total2` 
FROM `votes` WHERE `firstvote` = '2'");
    $r12r=mysqli_fetch_assoc($r12);

    $r13=mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total3` 
FROM `votes` WHERE `firstvote` = '3'");
    $r13r=mysqli_fetch_assoc($r13);
    ?>

现在我们回显结果以显示选项 1、2 和 3 的投票数

<?php echo number_format($r11r['total1'],0,',','.'); ?>
<? php echo number_format($r12r['total2'],0,',','.'); ?>
<? php echo number_format($r13r['total3'],0,',','.'); ?>

有什么办法可以缩短这段代码？我是 PHP 新手

Answer 1

您可以在查询中使用GROUP BY：

SELECT 
  firstvote,
  COUNT(*) AS count
FROM votes
GROUP BY firstvote

您会到达所有唯一的firstvote，并且使用此值计算行数。 如果您只想为此 firstvote 选择值，您可以使用此查询：

SELECT 
  firstvote,
  COUNT(*) AS count
FROM votes
WHERE firstvote IN (1, 2, 3)
GROUP BY firstvote

要按计数对值进行排序，您可以使用ORDER BY：

SELECT 
  firstvote,
  COUNT(*) AS count
FROM votes
GROUP BY firstvote
ORDER BY count DESC
LIMIT 3

DESC 一开始就意味着更大。

Answer 2

foreach(array(1,2,3) as $firstvote){
  $res=mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total` 
                                  FROM `votes` WHERE `firstvote` = '$firstvote' ");
  $r[$firstvote]=mysqli_fetch_assoc($res);
 }

foreach($r as $set){
  echo number_format($set['total'],0,',','.'); 
}

仅限高票：

$r['total']=0;
foreach(array(1,2,3) as $firstvote){
  $res=mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total` 
                                  FROM `votes` WHERE `firstvote` = '$firstvote' ");
  $tmp=mysqli_fetch_assoc($res);
  $r=max($tmp['total'],$r['total']);
 }


 echo number_format($r,0,',','.'); 

因为我现在不是你真正想做的事情，所以这是一种只获得所有结果中最高价值的解决方案。但是您应该使用您的 SQL 查询来执行此操作。添加类似ORDER BY total LIMIT 1 的内容

Answer 3

$result = mysqli_query($datacenter, "SELECT COUNT(firstvote) AS `total1` FROM `votes` WHERE `firstvote` in ('1','2','3') GROUP BY firstvote");

while ($row = mysqli_fetch_assoc($result)) {
    echo number_format($row['total1'], 0, ',', '.');
}

Answer 4

您可以使用 CASE 语法并在一个查询中完成所有操作

$sql = "SELECT
            SUM(CASE WHEN `firstvote` = 1 THEN 1 ELSE 0 END) AS total1,
            SUM(CASE WHEN `firstvote` = 2 THEN 1 ELSE 0 END) AS total2,
            SUM(CASE WHEN `firstvote` = 3 THEN 1 ELSE 0 END) AS total3
        FROM `votes`";

$res = mysqli_query($datacenter, $sql);
$row = mysqli_fetch_assoc($res);

echo number_format($row['total1'],0,',','.');
echo number_format($row['total2'],0,',','.');
echo number_format($row['total3'],0,',','.');

这将在单个结果行中返回名为 total1 total2 和 total3 的 3 列