大类ID:BigClassID=85
分类表:SmallClass
产品表:Products

select *,bbb.countpp from (SmallClass left join (select SmallClassID,count(*) as countpp from Products group by SmallClassID) bbb on SmallClass.ID=bbb.SmallClassID)  where BigClassID=$BigClassID order by XCODE asc
==================
分类信息统计功能的实现（sql多表left join）
相关文件:
1.products.php(分类信息)

相关数据库表:
大类ID:BigClassID=85
分类表:SmallClass
产品表:Products

核心功能:

（一条SQL语句实现2个表left join，并实现分类信息统计）
select *,bbb.countpp from (SmallClass left join (select SmallClassID,count(*) as countpp from Products group by SmallClassID) bbb on SmallClass.ID=bbb.SmallClassID)  where BigClassID=$BigClassID order by XCODE asc

核心代码:

分类信息页面:products.php
.......................................................................
<!-- 程序部分 -->
<?
$rs_small = new com("ADODB.RecordSet");
$sql_small="select *,bbb.countpp from (SmallClass left join (select SmallClassID,count(*) as countpp from Products group by SmallClassID) bbb on SmallClass.ID=bbb.SmallClassID)  where BigClassID=$BigClassID order by XCODE asc";
$rs_small->Open("$sql_small",$conn,1,1);
while(! $rs_small->eof)
{ 
?>
<LI><SPAN id=ppbr1 class=ppout><A
  href="products.php?BigClassID=<? echo $rs_small->Fields(BigClassID)->value; ?>&SmallClassID=<? echo $rs_small->Fields(ID)->value; ?>"><? echo $rs_small->Fields(XNAME)->value; ?>(
<?
if($rs_small->Fields(countpp)->value!="")
{
echo $rs_small->Fields(countpp)->value;
}
else
{
echo "0";
}
?>

)</A></SPAN></LI>
<?
$rs_small->MoveNext();
}?>
<!-- 程序部分 -->4216.com/view_434_4.html