saya ingin melakukan pencarian data, disini ada tabel buku
$judul=$_POST;
$id_pengarang=$_POST;
$id_penerbit=$_POST;
$isbn=$_POST;
$no_rak=$_POST;
$id_kategori=$_POST;
$tgl_masuk=date("Y-m-d");

dalam pencarian keynya adalah : judul, id_pengarang, id_penerbit,id_kategori, no_rak

			<div class="well well-lg" id="searchBox">
				<h2 class="text-center">Pencarian Buku</h2>
				<div class="text-center">
					<form role="form" method="GET">
						<select name="category">
							<option value="judul">Judul buku</option>
							<option value="pengarang">Pengarang</option>
							<option value="penerbit">Penerbit</option>
							<option value="subyek">Kategori</option>
							<option value="thn_terbit">Tahun terbit</option>
							<option value="isbn">ISBN</option>
						</select>
						<input type="text" placeholder="Masukkan kata kunci" name="keyword">
						<input type="submit" name="search" value="cari" class="btn btn-info">
					</form>
				</div>
			</div>

			<table class="table table-hover table-bordered">
				<tr>
					<th>No.</th>
					<th>Judul</th>
					<th>Pengarang</th>
					<th>Penerbit</th>
					<th>Kategori</th>
					<th>Tahun terbit</th>
					<th>No Rak</th>
					<th>ISBN</th>
					<th>Action</th>
				</tr>
             <?php
			  $sql="select * from buku,kategori where buku.id_kategori=kategori.id_kategori order by id_buku DESC";
			  $query=mysql_query($sql);
			  $no=1;
			  while($row=mysql_fetch_array($query)){
			  ?>
     <?php
		
	if(isset($_GET['category'])&&isset($_GET['keyword'])){
		$category = $_GET['category'];
		$keyword = $_GET['keyword'];

		//search for data in table buku where category contains keyword
		$sql = "SELECT * FROM buku WHERE $category LIKE '%$keyword%'";
		$result = mysqli_query($connection, $sql); 
		
		$count=mysqli_num_rows($result);	
	}else{
		$sql = "SELECT * FROM buku;";
		$result = mysqli_query($connection, $sql); 
		
		$count=mysqli_num_rows($result);	
	}


	if($count>0){
		$number = 1;	
		
		echo "<p>$count data ditampilkan.<p>";
		
		while($row = mysqli_fetch_assoc($result)) {
			$id = $row["id_buku"];
	        echo "<tr> <td>" . $number. "</td><td> " . 
	        $row["judul"]. "</td><td> " .
	        $row["pengarang"]."</td><td>".
	        $row["penerbit"]."</td><td>".
	        $row["nama_kategori"]."</td><td>".
	        $row["thn_terbit"]."</td><td>".
	        $row["deskripsi_fisik"]."</td><td>".
	        $row["isbn"]."</td><td>".