Question

我的表格categories有：id, name, subcategory_id, parent_id。另一个表格classifieds包含：classified_id, title, description, category_id。

我试图在每个类别中提取分类数量。所以它看起来像这样。

配件（10）
汽车（15）
约会（12）

我尝试了这样的尝试：

enter $catquery  = mysql_query("SELECT * FROM categories WHERE sub_id = '0' ORDER BY name ASC"); here

enter  $catrows = mysql_num_rows($catquery);  here
enter $catrows = mysql_num_rows($catquery); here
enter $query = "SELECT category_id, COUNT(title) AS `total` FROM classifieds WHERE classified_id = 'category_id' "; here
enter $result = mysql_query($query); here
enter while($row = mysql_fetch_assoc($result)){ $num_items_in_category[$row['category_id']] = $row['total'];  here

enter } echo "<li><a href='category.php?cat=".$row['id']."'>".$row['name']. $row['total']. "</a></li>"; here

谢谢费拉斯

Answer 1

COUNT是一个聚合函数，因此您可以一次获得所有计数。

我相信你要找的是

$query = "SELECT category-id, COUNT(title) AS `total` FROM classifieds WHERE classified-id = 'category-cat' GROUP BY category-id";
$result = mysql_query($query);

while($row = mysql_fetch_assoc($result)){
  $num_items_in_category[$row['category-id']] = $row['total']; 
}

这将为您提供关联数组，其中包含每个category-id

的记录数

Answer 2

你应该能够通过加入2个表来完成你想要的东西。

SELECT a.name, count(*) as cnt
FROM categories a
    join classifieds b
    on a.id = b.category_id
group by a.name

计算类别中的分类数量

2 个答案: