Database driven select box being empty on submit - php

Question

I am trying to submit a form value in a database with php. In form a select box value comes from database.
<?php include_once 'header.php';
$sql="SELECT uid,name FROM emitra_basic where block='$user'";
$result = $conn->query($sql);
//form validion
if(isset($_POST['submit']))
{
$eid =$_POST["eid"];
if($eid=="blank")
{
$flag=1;
$idErr="please Select E-MITRA";
}
$miatm =trim($_POST["miatm"]);
if(empty($miatm) || !preg_match("/^[a-zA-Z0-9 ]*$/",$miatm)) {
$flag=1;
$miErr="Please Enter Valid Id";
}
.............like this
if($flag==0)
{
$sqll="insert into **********";
}
//my form is
<form id="basic" method="post" name="basic">
<select class="select-style gender" name="eid">
<option value="blank">Please Select E-MITRA ID</option>
<?php
while($row=mysqli_fetch_array($result))
{
?>
<option value="<?php echo $row['uid']; ?>"><?php echo $row['uid']." (" . $row['name'] .")"; ?></option>
<?php
}
?>
</select>
<p class="contact"><label for="bid">Micro-ATM Serial No</label></p>
<input type="text" name="miatm" value ="<?php if (isset($miatm)) echo $miatm; ?>" /> <?php echo $miErr; ?>
<p class="contact"><label for="bid">Micro-ATM TID No</label></p>
<input type="text" name="tid" value ="<?php if (isset($tid)) echo $tid; ?>" /> <?php echo $tiErr; ?>
<input class="buttom" name="submit" id="submit" value="Add Me" type="submit">
Its seems Ok.but when i tried to submit the form if some of one field remain empty then its show blank value in select box.
how can i remain the same selected value in select box even if textbox remain empty.

Answer 1

You need to retain the value of drop down after form submit.
User selected attribute of select option.
<?php
if (isset($_POST['submit'])) {
$eid =$_POST["eid"];
if ($eid=="blank") {
$flag=1;
$idErr="please Select E-MITRA";
}
}
$sql="SELECT uid,name FROM emitra_basic where block='$user'";
$result = $conn->query($sql);
?>
<select class="select-style gender" name="eid">
<option value="blank">Please Select E-MITRA ID</option>
<?php
while($row=mysqli_fetch_array($result)) {
$selected = (isset($_POST["eid"]) && $_POST["eid"] == $row['uid']) ? 'selected="selected"' : '';
?>
<option value="<?php echo $row['uid']; ?>" <?php echo $selected;?>><?php echo $row['uid']." (" . $row['name'] .")"; ?></option>
<?php
}
?>
</select>

Answer 2

You need to use selected="" or selected="selected" after submission in your select tag as a attribute as:
<?
$sql="SELECT uid,name FROM emitra_basic where block='$user'";
$result = $conn->query($sql);
?>
<select class="select-style gender" name="eid">
<option value="blank">Please Select E-MITRA ID</option>
<?php
while($row=mysqli_fetch_array($result))
{
$selected = ((isset($_POST["eid"]) && $_POST["eid"] == $row['uid']) ? 'selected=""' : '');
?>
<option <?=$selected?> value="<?php echo $row['uid']; ?>"><?php echo $row['uid']." (" . $row['name'] .")"; ?></option>
<?php
}
if(isset($_POST['submit']))
{
$eid = $_POST["eid"];
if($eid=="blank")
{
$flag=1;
$idErr="please Select E-MITRA";
}
?>
</select>
Side Note:
In your question ist two lines are not inside the php, i hope this is type error.