如何使用php或javascript在下拉列表中将从mysql中提取的值设置为选定选项

Question

我正在从用户那里获取详细信息，并将其存储在mysql数据库中。我有一个更新页面，用户可以在其中更新值。此时，我希望允许用户从下拉列表中重新选择值，在该下拉列表中，最初输入的值应该已经被选中。如何将从数据库中提取的值设为选中选项。请用一些代码示例来解释。

$query="SELECT * from tablename where id=".$id;// I've assigned the value for id 
$rows=mysql_query($query,$connect); 
$row=mysql_fetch_array($rows,MYSQL_ASSOC);
?>
<select name="designation"> <?php
   echo "<option value=\"$row[OptionID]\" SELECTED>$row[OptionName]</option>\n";
?>
    <option value=sol1>sol1</option>
    <option value=sol2>sol2</option>
    <option value=sol3>sol3</option>
</select> 

Answer 1

为了使用数据库制作下拉选择框，您可以遵循以下给定的方法：

<?php
 $databaseHost = "localhost"; 
 $databaseUser = "root";
 $databasePassword = "password";
 $databaseName = "employee";
 $con=mysql_connect($databaseHost ,$databaseUser ,$databasePassword,'employee')or die ('Connection Error');
$dbSelected = mysql_select_db('foo', $con);
if (!$dbSelected) {
    die ('Can\'t use foo : ' . mysql_error());
}
 ?>
<strong> Select Designation : </strong> 
<select name="empName"> 
    <option value=""> -----------ALL----------- </option> 
    <?php
         $dd_res=mysqli_query($con, "Select DISTINCT designation from emp");
         while($r=mysqli_fetch_row($dd_res))
         { 
               echo "<option value='$r[0]'> $r[0] </option>";
         }
     ?>
</select>

旧MySQl的更新：

<?php
 $databaseHost = "localhost"; 
 $databaseUser = "root";
 $databasePassword = "password";
 $databaseName = "employee";
 $con=mysql_connect($databaseHost ,$databaseUser ,$databasePassword)or die ('Connection Error');
$db_selected = mysql_select_db('foo', $con);
if (!$db_selected) {
    die ('Can\'t use foo : ' . mysql_error());
}
 ?>
<strong> Select Designation : </strong> 
<select name="empName"> 
    <option value=""> -----------ALL----------- </option> 
    <?php
         $dd_res=mysql_query("Select DISTINCT designation from emp");
         while($r=mysql_fetch_row($dd_res))
         { 
               echo "<option value='$r[0]'> $r[0] </option>";
         }
     ?>
</select>

Answer 2

假设您有一个包含用户(ID、UserID、OptionID)的表和一个包含选项(OptionID、OptionName)或类似选项的表。

$get_details = $conn->query("SELECT * FROM table");
$data = $get_details->fetch_assoc();

$get_options = $conn->query("SELECT * FROM options");
while($row = $get_options->fetch_assoc()) {  
  if($row['OptionID'] == $data['OptionID'])
    echo "<option value=\"$row[OptionID]\" SELECTED>$row[OptionName]</option>\n";
  else
    echo "<option value=\"$row[OptionID]\">$row[OptionName]</option>\n";

}