php编程——sql查询（条件拼接）

function GetProducts($catagorys, $includeSubcatagory, $brandname='', $specialoffer, $pagesize, $pageindex, $orderby){
		$where = array(1);
		foreach($catagorys as $k=>$v){
			$catIDsql='SELECT cat_id FROM sdb_goods_cat WHERE cat_name=\''.$v.'\' ';
			$cat_rs[]=$this->db->selectrow($catIDsql);
		}
		foreach($cat_rs as $k=>$v){
			$cat_ids[] = $v['cat_id'];
		}
		if($includeSubcatagory){
			$where[] = ' AND c.parent_id in('.implode(',',$cat_ids).') OR c.cat_id in ('.implode(',',$cat_ids).') ';
		}else{
			$where[] = ' AND c.cat_id in ('.implode(',',$cat_ids).') ';
		}
		if($brandname){
			$where[] = ' AND g.brand = \''.$brandname.'\' ';
		}
		if($specialoffer){
			$where[] = ' AND g.iflimit = 1 OR g.is_groupbuy = \'true\' ';
		}
		switch($orderby){
			case 0:
				$ob = ' g.uptime DESC';
			break;
			case 1:
				$ob = ' g.uptime ';
			break;
			case 2:
				$ob = ' p.price DESC';
			break;
			case 3:
				$ob = ' p.price ';
			break;
			case 4:
				$ob = ' g.buy_count DESC';
			break;
			case 5:
				$ob = ' g.buy_count ';
			break;
			case 6:
				$ob = ' g.score DESC ';
			break;
			case 7:
				$ob = ' g.score ';
			break;
			
		}
		$sql='SELECT p.product_id,p.bn,p.name,g.cat_id,c.cat_name,p.price,p.mktprice,g.buy_count,g.score,g.uptime,g.thumbnail_pic,g.small_pic,g.big_pic,g.intro,g.params,g.supplier_id,g.score,g.last_modify,g.buy_count,g.store FROM sdb_goods as g,sdb_goods_cat as c,sdb_products as p WHERE g.goods_id=p.goods_id AND g.cat_id = c.cat_id AND 1='.implode(' ',$where).' ORDER BY '.$ob.' limit '.$pagesize*($pageindex-1).','.$pagesize*$pageindex;
		$result=$this->db->select($sql);
		if(!$result){
			$result[0]=array();
		}
		return $result;
	}