常用的PHP与SQL语句

<?php
$conn=mysql_connect("localhost","root","root");
mysql_select_db("db_database17",$conn);
mysql_query("set names gb2312");
?>
<?php
$sql1=mysql_query("select usernc,face,ip,email,qq from tb_user where id='".$info["userid"]."'",$conn);
$info1=mysql_fetch_array($sql1); 
echo $info1["face"];
?>
action="savereg.php"
<input type="text" name="usernc"
<input type="text" name="userpwd"
<input type="text" name="truename" 
<?php
if(mysql_query("insert into tb_user(usernc,userpwd,truename,email,qq,tel,ip,address,face,regtime,sex,usertype) values('".$usernc."','".md5(trim($_POST["userpwd"]))."','".$_POST["truename"]."','".$_POST["email"]."','".$_POST["qq"]."','".$_POST["tel"]."','".$ip."','".$_POST["address"]."','".$_POST["face"]."','".date("Y-m-d H:i:s")."','".$_POST["sex"]."','0')",$conn)){
if($_SESSION["unc"]!=""){
    session_unregister("unc");
   }
session_register("unc");
   $_SESSION["unc"]=$usernc;   
   echo "<script>alert('注册成功！');history.back();</script>";
}else{
   echo "<script>alert('注册失败！');history.back();</script>";
}
?>
<?php
    $sql=mysql_query("select count(*) as total from tb_leaveword ",$conn);//把查询的结果存入total中
    $info=mysql_fetch_array($sql);
    $total=$info[total];
    if($total==0){
     echo "<div align=center>对不起，暂无留言！</div>";
    }else{
      if(!isset($_GET["page"]) || !is_numeric($_GET["page"])){
         $page=1; 
      }else{
         $page=intval($_GET["page"]);
      }
      
      $pagesize=3;
      if($total%$pagesize==0){
         $pagecount=intval($total/$pagesize);
      }else{
         $pagecount=ceil($total/$pagesize);
      }
      $sql=mysql_query("select * from tb_leaveword order by createtime desc limit ".($page-1)*$pagesize.",$pagesize ",$conn);
      while($info=mysql_fetch_array($sql)){
     
      ?>
<table width="520" height="5" border="0" align="center" cellpadding="0" cellspacing="0">
      <tr>
        <td></td>
      </tr>
    </table>
      <table width="550" height="155" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#FCD424">
        <tr>
          <td bgcolor="#FFFFFF" valign="top"><table width="550" height="24" border="0" align="center" cellpadding="0" cellspacing="0">
            <tr>
              <td width="450" background="images/dh_back_1.gif">&nbsp;主&nbsp;&nbsp;题：<?php echo unhtml($info["title"]);?></td>
              <td width="100" background="images/dh_back_1.gif"><div align="center">
     <script language="javascript">
       function openeditwindow(x){
    
       window.open("editleaveword.php?id="+x,"newframe","top=100,left=200,width=450,height=280,menubar=no,location=no,scrollbars=no,status=no");
      
     }
     
     </script>
    <?php 
      $sqlu=mysql_query("select usernc from tb_user where id='".$info["userid"]."'",$conn);
      $infou=mysql_fetch_array($sqlu);
      if($infou["usernc"]==$_SESSION["unc"]){
    ?> 
       <a href="javascript:openeditwindow(<?php echo $info[id];?>)" class="a1">编辑</a>
    <?php
     }
    ?> 
    &nbsp;
    <?php
     if($_SESSION["unc"]!=""){
      $sqld=mysql_query("select usertype from tb_user where usernc='".$_SESSION["unc"]."'",$conn);
               $infod=mysql_fetch_array($sqld);
      if($infod["usertype"]==1){ 
     ?>
     <a href="javascript:if(window.confirm('确定删除该留言信息么？')==true){window.location.href='deleteleaveword.php?id=<?php echo $info[id];?>';}" class="a1">删除</a>
    <?php
      }
     }
    ?>
     </div></td>
            </tr>
          </table>
            <table width="550" height="5" border="0" align="center" cellpadding="0" cellspacing="0">
              <tr>
                <td></td>
              </tr>
            </table>
   
    <table width="550" height="120" border="0" align="center" cellpadding="0" cellspacing="0">
              <tr>
                <td width="150" height="90"><div align="center"><img src="<?php
     $sql1=mysql_query("select usernc,face,ip,email,qq from tb_user where id='".$info["userid"]."'",$conn);
     $info1=mysql_fetch_array($sql1); 
     echo $info1["face"];
     
     ?>" /><br><?php echo $info1["usernc"];?></div></td>
                <td width="10" background="images/line_down.gif"></td>
                <td width="390" rowspan="2"><?php echo unhtml($info["content"]);?></td>
              </tr>
              <tr>
                <td height="30"><div align="center"><img src="images/email.gif" width="45" height="16" alt="<?php echo $info1[email];?>"/><img src="images/ip.gif" width="55" height="16" alt="<?php echo $info1[ip];?>"/><img src="images/qq.gif" width="45" height="16" alt="<?php echo $info1[qq];?>"/></div></td>
                <td width="10" background="images/line_down.gif"></td>
              </tr>
            </table>
   
    </td>
        </tr>
      </table>
    <?php
    }
    }
   ?>
   
   
   
    <table width="550" height="25" border="0" align="center" cellpadding="0" cellspacing="0">
         <tr>
           <td width="351"><div align="left">共有留言&nbsp;<?php echo $total;?>&nbsp;条&nbsp;每页显示&nbsp;<?php echo $pagesize;?>&nbsp;条&nbsp;第&nbsp;<?php echo $page;?>&nbsp;页/共&nbsp;<?php echo $pagecount;?>&nbsp;页</div></td>
           
           <td width="199"><div align="right"><a href="<?php echo $_SERVER["PHP_SELF"]?>?page=1" class="a1">首页</a>&nbsp;<a href="<?php echo $_SERVER["PHP_SELF"]?>?page=<?php 
   if($page>1) 
    
     echo $page-1;
    else
     echo 1; 
     ?>" class="a1">上一页</a>&nbsp;<a href="<?php echo $_SERVER["PHP_SELF"]?>?page=<?php 
   if($page<$pagecount) 
    
     echo $page+1;
    else
     echo $pagecount; 
     ?>