请求讲解一下continue的用法：

请求讲解一下continue的用法：
while($row = $dsql->GetArray()) {
$tb = str_replace('#@__',$cfg_dbprefix,$row['addtable']);
if(empty($tb) || isset($doarray[$tb]) )
{
continue;?
} else {
$sql = "INSERT INTO `#@__arctiny`(id,typeid,typeid2,arcrank,channel,senddate,
sortrank,mid) SELECT aid,typeid,0,arcrank,channel,senddate,0,mid FROM `$tb` ";
$rs = $dsql->executenonequery($sql);
$doarray[$tb] = 1;
}
}
请问这里的continue;是什么意思?在这段代码中如果不写它,效果与写上它有何不同?