php根据查询条件拼接sql语句

用变量$i,默认等于0是第一次，大于0是多次 ,key和val是一个一维数组 
 if($status){
$where_arr['goods_status='] = $status;
}
if($goods_id){
$where_arr['id='] = $goods_id;
}
if($goods_count == 1){
$where_arr['goods_count='] = 0;
}
if($goods_name){
$where_arr['goods_name like'] = "'%$goods_name%'";
}
if($goods_category){
$where_arr['goods_category='] = $goods_category;
}
  if(count($where_arr) > 0) {
 
$where = 'where ';
$i=0;
foreach ($where_arr as $k=>$val){
  if($i==0) {
$where  .= $k.$val;
}else{
$where  .= ' and '.$k.$val;
 }
   $i++;
 }