php中mysql一次连接只能查询一次么？

1" . mysql_error());
mysql_select_db('mydb', $link) or die ('很抱歉，没有您要查询的内容！2' . mysql_error());
$query = "select * from mytable where oid_date=$_GET[oid_date] and oid_emlfilename='$_GET[oid_emlfilename]'";
$ok_result = mysql_query($query) or die("很抱歉，没有您要查询的内容！aa");
if($ok_result = 0){echo "已经是最后一条记录了。";}else{$row = mysql_fetch_array($ok_result, MYSQL_ASSOC);
echo $query;
echo $row[oid_date];
$nexturl = "cleardate.php?oid_date=$row[oid_date]&oid_emlfilename=$row[oid_emlfilename]";}$query = "select * from mytable where oid_date=$_GET[oid_date] and oid_emlfilename='$_GET[oid_emlfilename]'";
$ok_result = mysql_query($query) or die("很抱歉，没有您要查询的内容！3");
$row = mysql_fetch_array($ok_result, MYSQL_ASSOC);?>代码的意思就是根据关键值oid_date先取当前条的上一条内容，将关键值存入$nexturl 准备传递；然后在查询当前条，输出出来。
$row = mysql_fetch_array($ok_result, MYSQL_ASSOC);这一行总是报错mysql_fetch_array(): supplied argument is not a valid MySQL result ， 补充： 第一条查询语句应该是select * from mytable where oid_date>$_GET[oid_date] order by oid_date desc limit 1