Question

让我先介绍一下我想要实施的最终解决方案。

我想显示特定类别中的类别和任意三个或少于三个子类别。

表： listing_info

listing_id(PK) | Market | Project_Name 
1              | A      | A.a  
2              | A      | A.b   
3              | A      | A.c  
4              | A      | A.d   
5              | A      | A.e  
6              | A      | A.f   
7              | B      | B.a  
8              | B      | B.b   
9              | B      | B.c  
10             | B      | B.d   
11             | C      | C.a   
12             | C      | C.b   
13             | D      | D.a   
14             | D      | D.b   
15             | D      | D.c   
16             | D      | D.d   
17             | D      | D.e   
18             | E      | E.a   
19             | F      | F.a

此处市场为类别，Project_Name为子类别。

我使用了两种方法，需要知道选择哪个以及为什么？此外，我正在寻找任何更好的解决方案或任何可以对现有解决方案进行的优化

方法一：

使用简单查询并进一步调用db以获取子类别。这可以通过使用ajax分页或onload分页来优化

我们可以将LIMIT AND OFFSET与每个加载事件设置为某个数字x的倍数。

$data = sql::read("SELECT Market FROM listing_info GROUP BY Market LIMIT ? OFFSET ?");

<?php foreach($data as $d)
{ ?> 
<div class="Market">
  <h2> <?php echo $d->Market ?> </h2>
  <?php 
  $subcat = sql::read("SELECT Project_Name FROM listing_info WHERE Market =".$d->Market."LIMIT 3");
  foreach($subcat as $sc) ?>
    <h3 class="Project_Name"> <?php echo $sc->Project_Name ?> <h3>
  <?php } ?>   
</div>
<?php } ?>

的方法2：

我们可以一次性调用这些值，包括每个类别中的任意三个或少于三个子类别。

<?php 

    $data=sql::read("SELECT t1.Market, t1.Project_Name
    , COUNT(t2.listing_Id) AS cnt
    FROM listing_info AS t1
    LEFT JOIN listing_info AS t2
    ON (t1.Project_Name, t1.listing_Id) <= (t2.Project_Name, t2.listing_Id)
    AND t1.Market = t2.Market
    GROUP BY t1.listing_Id
    HAVING cnt <= 3
    ORDER BY t1.Market, cnt
    ");

    $mydata = objectToArray($data); // Converting object array to associative array

    //And then finding the count of each category 

    $counted = array_count_values(array_map(function($value){return $value['Market'];}, $mydata));

 //var_dump($counted) 
 /* array
  'A' => int 3
  'B' => int 3
  'C' => int 2
  'D' => int 3
  'E' => int 1
  'F' => int 1
  */
$index = 0;
foreach($counted as $k=>$v)
{
  ?>
  <div class="Market">
      <h2> <?php echo $k ?> </h2> 
       <?php for($m=0; $m < $v; $m++)
       { ?>
       <h3> <?php echo $mydata[$index]["Project_Name"]; ?> <h3>
       <?php $index++; } ?> 
  <div>
<?php } ?>

第一种方法提供了ajax的好处，但是关注的是多个sql调用，第二种方法提供了较少sql调用的好处，但我无法使用ajax完成它。

任何帮助优化代码或任何其他更好的解决方案都将受到赞赏

提前致谢

Answer 1

我找到的一个可能的解决方案是使用临时表并为每个类别包含Id，然后使用BETWEEN子句可以限制类别，在每个后续的ajax请求中更改BETWEEN A的值？和B？

    $maketemp = "
           CREATE TEMPORARY TABLE temp_Market_Tbl2 (
            `Id` int NOT NULL AUTO_INCREMENT,
            temp_market VARCHAR(50) NOT NULL,
            PRIMARY KEY (`Id`)) AUTO_INCREMENT=0 ;";

        mysql_query($maketemp);
        $insert = "INSERT INTO temp_Market_Tbl2
             (temp_market)
             SELECT Market FROM listing_info GROUP BY Market;
           "; 
         mysql_query($insert);

 $data2=sql::read("SELECT b.* FROM temp_market_tbl2 b INNER JOIN (SELECT t1.Market, t1.Project_Name
        , COUNT(t2.listing_Id) AS cnt
        FROM listing_info AS t1
        LEFT JOIN listing_info AS t2
        ON (t1.Project_Name, t1.listing_Id) <= (t2.Project_Name, t2.listing_Id)
        AND t1.Market = t2.Market
        GROUP BY t1.listing_Id
        HAVING cnt <= 3
        ORDER BY t1.Market, cnt) a ON a.Market = b.temp_market WHERE b.Id BETWEEN 1 AND 4 ORDER BY b.Id ");

          var_dump($data2);

具有多个调用的常规查询与使用PHP处理的复杂查询

1 个答案: