php多条件附加查询

php多条件叠加查询

header("Content-Type:text/html;charset=utf-8");
include("../manage/include/function.php");
	$brand=substr($_POST["brand"],0,strlen($_POST["brand"])-1); 
	$color=substr($_POST["color"],0,strlen($_POST["color"])-1); 
	$caizhi=$_POST["caizhi"];
	$style=$_POST["style"];
	$kucun=$_POST["kucun"];
	echo($brand."
");
	echo($color."
");
	echo($caizhi."
");
	echo($style."
");
	echo($kucun);
	
	$q="select * from pros_pro where (1=1)";
	if($brand!=null){
		$q=$q+"and psp_brand in(".$brand.")";
	}
	if($color!=null){
		$q=$q+"and psp_color in(".$color.")";
	}
	if($caizhi!=null){
		$q=$q+"and psp_caizhi='".$caizhi."'";
	}
	if($style!=null){
		$q=$q+"and psp_style='".$style."'";
	}
	if($kucun!=null){
		$q=$q+"order by psp_stock desc";
	}else
	{
		$q=$q+"order by psp_id desc";
	}
	

	$rows=query($q);
	if($row=mysql_fetch_array($rows))
	{
		do{
?>
			
		}
	else
	{?>
		没有符合条件的信息，请重新定义搜索条件!
		}
	?>	

这个代码有神马问题？为什么会报错：Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in /data/home/hmu069081/htdocs/products/get_post.php on line 37
且没有符合条件的信息，可是我选的条件明明是有记录的
------解决方案--------------------
把所有形如
$q=$q+"and psp_brand in(".$brand.")";
这样的语句，改成形如这样的
$q = $q ." and psp_brand in(".$brand.")";
或
$q .= " and psp_brand in(".$brand.")";