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< ?php
$sql = "select Users.*,Answer.* from `Users`,`Answer` where Users.U_id = Answer.Uid and Answer.Qid = '$Que_id' and Answer.A_re = 0 order by Answer.A_date Asc ";
//找出问题为5的所有回答 并且pid=0(无回复)
$result = mysql_query($sql);
$num = mysql_num_rows($result); //获取行数
if ($num == '0')
{
echo "不存在";
}
else
{
echo "存在";
｝
? >