如何检索存储的数据库数据（即从下拉列表中选择的数据）作为下拉列表中的选定数据

Question

到目前为止我所做的是将下拉选择的数据存储到数据库中，我现在想要的是基于在文本框中输入的用户名并单击搜索按钮，要选择的下拉项是存储在数据库中的数据以及用户可以根据需要选择的值列表。

我只想知道如何用来自数据库的选定数据替换文本 Select from here 以及允许用户在下拉列表中根据需要编辑数据并在单击后再次将其保存在数据库中提交按钮。

存储数据时代码如下

<?php
if( $_POST['registerbtn']){
$getuser=    mysql_real_escape_string(trim($_POST['user']));
$selected_value = $_POST['selectID'];
if($selected_value != 0){
require("./connect.php");
$query=mysql_query("SELECT * FROM user_details WHERE username='$getuser'");
$numrows= mysql_num_rows($query);
if($numrows == 0) { 
mysql_query("INSERT INTO user_details  VALUES (  '','$getuser','$selected_value')");
}
 else
$errormsg = "There is already a user with that username ." ;
mysql_close();
}
else
 $errormsg = "You  must select a linecard";
}
//code to fill dropdown 
require("./connect.php");
$sql = "SELECT select_id, linecard_name FROM selection ". "ORDER BY linecard_name";
$rs = mysql_query($sql);
$options = "<option value = '0'>  Select  from here </option>";
while($rownw = mysql_fetch_array($rs)){
$options .= "<option value = ".$rownw['select_id']." > ".$rownw['linecard_name']. " </option> ";
}
mysql_close() ;

$form = "<form action='./reg.php'  method='post'>
<table>
<tr>
<td>  </td>
<td>  <font color='red'> $errormsg </font> </td>
</tr>

<tr>
<td>  Username  </td>
<td>  <input type='text' name='user'  value='$getuser' />  </td>
</tr>

<tr>
<td> Select  Linecard </td>
<td>  <Select name='selectID' > $options  </select> </td>
</tr>

<tr>
<td>   </td>
<td>  <input type='submit' name='registerbtn' value='Register' />  </td>
</tr>

</form>";

echo $form;
?>      

根据文本框中写入的用户名从数据库中检索数据到下拉列表的代码如下

<?php
if( $_POST['savebtn']){
$search = $_POST['search'];
if($search == '' )
{
$errormsg1 = "Enter something in the search box";
}
else
{
require("./connect.php");
$query = mysql_query("SELECT  * FROM user_details  WHERE  username = '$search'");
$numrows= mysql_num_rows($query);
$rows=mysql_fetch_assoc($query);
if($numrows == 1)
{
$getuser = $rows['username'];
$select_id= $rows['linecard_id'];
//selection table where linecard_name is stored along with select_id   for the linecard_name to be displayed 
$query1  = mysql_query("SELECT *  FROM selection  WHERE  select_id = '$select_id' ") ;
$rows1=mysql_fetch_assoc($query1);
$linecard_name= $rows1['linecard_name'];
echo $linecard_name;

$sql = "SELECT select_id, linecard_name FROM selection ". "ORDER BY linecard_name";
$rs = mysql_query($sql);
while($rownw = mysql_fetch_array($rs)){
if( $select_id == $rownw['select_id'])  {
echo $select_id;
$options .= "<option value = ". $select_id ." > " .$linecard_name. " </option> ";
}
}

}
else
$errormsg1 = "Username was Not found";
mysql_close() ;
}
}

?>

<?php
$form ="<form action='ad.php' method='post' id='search' >
<div class='place'>
<tr>
<td>  </td>
<td>  <font color='red' > $errormsg1 </font> </td>
</tr>

<div class='frm2'> <input  type='text'  size='15'  value='$search'  name='search'    /> </div>
<div class='frm3'>      <input type='submit'   name='savebtn'  /> </div>
<div class='clear'> </div>
</div> 
</form>";
echo $form;
?>

<?php
require("./connect.php");
$sql = "SELECT select_id, linecard_name FROM selection "."ORDER BY linecard_name";
$rs = mysql_query($sql);
$options = "<option value = '0'>  Select  from here </option>";
while($rownw = mysql_fetch_array($rs)){
$options .= "<option value = ".$rownw['select_id']." > ".$rownw['linecard_name']. " </option> ";
}
mysql_close() ;
$form = "<form action='./reg.php'  method='post'>
<table>
<tr>
<td>  </td>
<td>  <font color='red'> $errormsg </font> </td>
</tr>
<tr>
<td>  Username  </td>
<td>  <input type='text' name='user'  value='$getuser' />  </td>
</tr>

<tr>
<td> Select  Linecard </td>
<td>  <Select name='selectID' > $options  </select> </td>
</tr>
<tr>
<td>   </td>
<td> <input type='submit' name='savebtn' value='Save' />   </td>
</tr>
</form>";
echo $form;
?>

Answer 1

您可以将选项存储到一个变量中，我们称之为 $options，然后将其插入到您的 $form 变量中。最后你可以随心所欲地回显它。

<?php
require("./connect.php");
$sql = "SELECT select_id, linecard_name FROM selection ". "ORDER BY linecard_name";
$rs = mysql_query($sql);

$options = "<option value= '0' >  Select  from here </option>";
while($rownw = mysql_fetch_array($rs)){
    $options .= "<option value = ".$rownw['select_id']." > ".$rownw['linecard_name']. " </option> ";
} 
mysql_close() ;

$form = "<form action='./reg.php'  method='post'> 
<table>
<tr> 
<td>  </td>
<td>  <font color='red'> $errormsg </font> </td> 
</tr> 

<tr>
<td>  Username  </td>
<td>  <input type='text' name='user' />  </td> 
    </tr> 

<tr>
<td> Select  Linecard </td> 
<td> <Select name='selectID'> $options </select>
</tr> 

<tr>
<td>   </td>
<td> <input type='submit' name='registerbtn' value='Register' />   </td> 
</tr>

</table> 
</form>"; 

echo $form;

Answer 2

请更改您的代码如下：

    <?php
        require("./connect.php");
        $sql = "SELECT select_id, linecard_name FROM selection ". "ORDER BY linecard_name";
        $rs = mysql_query($sql);

        echo "<form action='./reg.php'  method='post'> 
            <table>
              <tr> 
                <td>  </td>
                <td>  <font color='red'> $errormsg </font> </td> 
             </tr>         
             <tr>
                <td>  Username  </td>
                <td>  <input type='text' name='user' />  </td> 
             </tr>         
             <tr>
                <td> Select  Linecard </td> 
             <td>";
     ?>
           <Select name='selectID'>  
              <option value= '0' >  Select  from here </option>  
              <?php

                   while($rownw = mysql_fetch_array($rs)){
                     echo "<option value = ".$rownw['select_id']." > ".$rownw['linecard_name']. " </option> ";
                    }
                ?>
               </select>    
             </tr> 

            <tr>
                <td>   </td>
                <td> <input type='submit' name='registerbtn' value='Register' />   </td> 
            </tr>

        </table> 
     </form>    
 <?php   
    mysql_close() ;
 ?>

Answer 3

试试这个

<?php
require("./connect.php");
$sql = "SELECT select_id, linecard_name FROM selection ". "ORDER BY linecard_name";
$rs = mysql_query($sql);
?>
<form action="<?php echo $_SERVER['SCRIPT_NAME']; ?>" method="POST">
<table>
<tr> 
<td>  </td>
<td>  <font color='red'> $errormsg </font> </td> 
</tr> 

<tr>
<td>  Username  </td>
<td>  <input type='text' name='user' />  </td> 
</tr> 
<?php   while($rownw = mysql_fetch_array($rs)){ ?>
<tr>
<td> Select  Linecard </td> 
<td> <Select name='selectID'> <?php  echo "<option value = ".$rownw['select_id']." > ".$rownw['linecard_name']. " </option> "; ?>  </select>
</tr> 
<?php } //end of while loop ?>
<tr>
<td>   </td>
<td> <input type='submit' name='registerbtn' value='Register' />   </td> 
</tr>

</table> 
</form>;