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PHP code:


$query=mysql_query("select * from yonghu_t where yonghu_yhmm=$addusername");
if($query){
echo "<script>";
echo "alert(¡®Óû§ÃûÒѾ­´æÔÚ¡¯); window.history.go(-1);";
echo "</script>";
}else{

$sql="insert into yonghu_t (yonghu_yhmc,yonghu_yhmm,yonghu_yhsf,yonghu_lxfs,yonghu_yx,yonghu_jdsj) values('$addusername','$password1','$yhsf','$lxfs','$addemail',$time)";
echo "<br>".$sql;
$return=mysql_query($sql);
}


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if($query)

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"select * from yonghu_t where yonghu_yhmm=\"".$addusername."\""

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"select * from yonghu_t where yonghu_yhmm=$addusername"====¡·"select * from yonghu_t where yonghu_yhmm='$addusername'"

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mysql_query µÄ·µ»ØÖµ false²»ÊDz鲻µ½Êý¾Ý£¬¶øÊÇÄãµÄsqlÓï¾äÓдíÎó¡£
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$query=mysql_query("select count(*) from yonghu_t where yonghu_yhmm=$addusername");

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PHP code:

$sql = "se