<div class="demo-container">
<div class="container-form">
<form action="" method="post" class="d-flex flex-sm-row flex-column align-items-center justify-content-center"> 
<select name="search_option" class="form-select">
<option value="song" <?php echo ($_POST['search_option']=='song'?'selected':'')?>>Song Title</option>
<option value="artist" <?php echo ($_POST['search_option']=='artist'?'selected':'')?>>Artist</option>
<option value="year" <?php echo ($_POST['search_option']=='year'?'selected':'')?>>Year</option>
</select> 
<input name="search" id="search" class="form-control me-1 shadow-none search-input mwd-single-space-only" autocomplete="off" type="search" aria-label="Search" 
value="<?php if(isset($_POST['search'])) echo $_POST['search'];?>" >
<input id="button_search" type="submit" name="submit" class="btn btn-secondary btn-search" value="Search"> 
</form>
</div> 
<?php
if(isset($_POST['submit'])){ 
$search_value = $_POST["search"]; 
if(($_POST['search_option']) == "song") {
$option_selected = "song";
echo '<div class="mwd-search-info">Song title: “<span class="highlight-01">'.$search_value.'</span>”</div>'; 
} 
if (($_POST['search_option']) == "artist") { 
$option_selected = "artist";
echo '<div class="mwd-search-info">Artist “<span class="highlight-02">'.$search_value.'</span>”</div>'; 
}
if (($_POST['search_option']) == "year") { 
$option_selected = "year";
echo '<div class="mwd-search-info">Year “<span class="highlight-03">'.$search_value.'</span>”</div>'; 
} 
}
?> 
<div class="container-results"> 
<?php
$conn = new mysqli ("server", "user", "password", "database");
mysqli_set_charset ($conn, "utf8");
if ($conn -> connect_error) {
die ("Error: " . $conn->connect_error);
} 
if(isset($_POST['submit'])) {
$sql = "SELECT * FROM top_5000_songs WHERE ".$option_selected." LIKE '%$search_value%' LIMIT 0, 40";
$result = $conn -> query($sql);
if ($result -> num_rows > 0) {
echo "<table id=\"table-demo\" class=\"table table-striped\">";
echo "<thead>";
echo "<tr>";
echo "<th>Song Title</th>";
echo "<th>Artist</th>";
echo "<th>Year</th>";
echo "</tr>";
echo "</tbody>";
echo "<tbody>"; 
while ($row = $result -> fetch_assoc()) {
$song = $row["song"];
$artist = $row["artist"];
$year= $row["year"];
if(($_POST['search_option']) == "song") {
$song = preg_replace("/($search_value)/i", '<span class="highlight-01">$1</span>', $song); 
} 
else if(($_POST['search_option']) == "artist") {
$artist = preg_replace("/($search_value)/i", '<span class="highlight-02">$1</span>', $artist); 
} 
else if(($_POST['search_option']) == "year") {
$year= preg_replace("/($search_value)/i", '<span class="highlight-03">$1</span>', $year); 
} 
echo "<tr>";
echo "<td>" . $song . "</td>";
echo "<td>" . $artist . "</td>";
echo "<td>" . $year. "</td>"; 
}
echo "</tr>";
echo "</tbody>";
echo "</table>"; 
} 
else {
echo "No records found";
} 
}
$conn -> close();
?> 
</div>
</div>