PHP下拉列表在重新加载时保持

Question

I am new to PHP and have just started the professional development in this language. I have created a dynamic dropdown list in php as under:

$sql="select DISTINCT State from branchinfo";
    $result = $conn->query($sql);
    if($result->num_rows > 0)
    {
        echo "< SELECT NAME='states'>";
        while($row=$result->fetch_assoc())
        {
            echo "< OPTION NAME = '" . $row['State'] . "'" . " VALUE = '" . $row['State'] . "'>" . $row["State"]; 
        }<br>
        echo "< /SELECT>";
    }
    echo "< INPUT TYPE='submit' name='submit' value='submit'>";

Problem is when I select a state and click on submit, the list reloads and my selection is lost, the first option gets selected by default. I have tried to embed the script within OPTION but it didn't worked, I tried it as under:

    echo "< OPTION NAME='" . $row['State'] . "'" . " VALUE='" . $row['State'] . "'" . if(isset($_POST["submit"])){ if($_POST["states"] == $row['State']) echo "selected";} . " >" . $row["State"];<br>

I am not using any javasrcipt / jquery till now on this page and not planning to use it either. plz provide a solution within this code. Please help.

Some additional information

The mthod i tried as mentioned above, works fine on hardcoded static drop downlist items written in html form. It stops working for dynamically generated list.

Answer 1

You have to add dropdown inside form tag, then it will work.

$sql = "select DISTINCT State from branchinfo";

$result = $conn->query($sql);

echo "<form method='POST'>";

if ($result->num_rows > 0) {

    echo "<SELECT NAME='states'>";

    while ($row = $result->fetch_assoc()) {

        $sel = ( $_POST['states'] == $row['State'] ) ? "selected" : "";

        echo "< OPTION NAME = '" . $row['State'] . "'" . " VALUE = '" . $row['State'] . "' " . $sel . ">" . $row["State"] . "</OPTION>";
    }
    echo "</SELECT>";
}
echo "<INPUT TYPE='submit' name='submit' value='submit'>";
echo "</form>";

Answer 2

Use session to remember your choice. And when the page is reloaded just retrieve your previous selected value.

like

    while($row=$result->fetch_assoc())
        {
if($sessionvalue==$row['State']){
echo "< OPTION SELECTED NAME = '" . $row['State'] . "'" . " VALUE = '" . $row['State'] . "'>" . $row["State"]; 
}else{
echo "< OPTION NAME = '" . $row['State'] . "'" . " VALUE = '" . $row['State'] . "'>" . $row["State"]; 
}

        }