Fetch data from mysql to textarea, but if not exist print null - php

Question

I made some little translator.
And if word exist in database all is ok. But if word didnt exist in database, word isnt printed. I add some code to print if result is empty but didnt work.
Any idea why word that not exist in database isnt printed?
Here is code:
<p><form method="post" action="prevedi.php">
<textarea id="prevedi" name="prevedi" style="margin: 2px; height: 137px; width: 380px;">
<?php
echo htmlentities($_POST['prevedi']);
?>
</textarea>
<textarea id="prevod" disabled="disabled" name="prevod" style="margin: 2px; height: 137px; width: 380px; border: 0px;" readonly>
<?
if (isset($_POST['prevedi'])) {
//Kreci
$prevedi = htmlentities($_POST['prevedi']);
$prevedi = explode(" ",$prevedi);
foreach ($prevedi as $word) {
$slovo = $word[0];
$result = mysqli_query($con,"SELECT * FROM $slovo WHERE srpski='$word'");
if (!empty($result)) {
while($row = mysqli_fetch_array($result))
{
$prevod .= $row['romski']." ";
}
}
else
{
$prevod .= "".$word." ";
}
}
echo $prevod;
//Kraj isset
}
?>
</textarea><br>
<input name="translate" type="submit" value="Translate"/>
</form>
</p>

Answer 1

Because your result is not empty. You should check if $result number of rows is > 0
if ($result->num_rows > 0) {
while($row = mysqli_fetch_array($result)){
$prevod .= $row['romski']." ";
}
}else{
$prevod .= $word." ";
}

Answer 2

i think you have to initialize $prevod before assigning it the way you did.
$prevod = "";
if (!empty($result)) {
while($row = mysqli_fetch_array($result))
{
$prevod .= $row['romski']." ";
}`enter code here`
}
else
{
$prevod .= "".$word." ";
}
}
echo $prevod;