Pfthb

<ul class="p-b-54">
 <li class="p-t-4">
 <a href="#" class="s-text13 active1">
 All
 </a>
 </li>
 <?php 
 $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops` ORDER BY `Id` DESC LIMIT 100 ";
 $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
 if(mysqli_num_rows($run_query_category) > 0)
 while($row = mysqli_fetch_array($run_query_category))
 $product_Category = $row["Category"]; 
 ?>

 <li class="p-b-9">
 <a href="#" class="s-text7">
 <?php 
 $prod_Cat = explode(", ", $product_Category);
 echo $prod_Cat[0]; 
 ?>
 </a>
 </li>
<?php 
 
 
?>
</ul>

This is how they are saved in the database

Electronics, Computers & Accessories, Computers & Tablets, Laptops, Traditional Laptops
Electronics, Computers & Accessories, Computers & Tablets
Electronics, Computers & Accessories, Computers & Tablets, Laptops, 2 in 1 Laptops
Electronics, Computers & Accessories, Computers & Tablets, Tablets
Electronics, Computers & Accessories, Monitors
Electronics, Accessories & Supplies, Audio & Video Accessories, TV Accessories & Parts, TV Ceiling & Wall Mounts
Electronics, Accessories & Supplies, Audio & Video Accessories
Electronics, Camera & Photo, Digital Cameras, DSLR Cameras
Electronics, Television & Video, Televisions
Electronics, PC Gaming, Gaming Computers
Gaming Monitors
Gaming Laptops 

This is what am expecting

Electronics
Gaming Monitors
Gaming Laptops 

I want to get rid of all duplicate electronics

So far my output is

Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Gaming Monitors
Gaming Laptops 

I have a list of categories stored in mysql database with comma separated words.
I have managed to display the first word form each string. Though my intentions are getting unique categories after extracting the first words. But as you can see am getting all duplicate content. How do i get rid of them?

IF YOU WANT TO CREATE THE TABLE THIS IS THE SQL QUERY

-- --------------------------------------------------------

--
-- Table structure for table `gaminglaptops`
--

CREATE TABLE `gaminglaptops` (
 `Id` int(11) NOT NULL,
 `Category` text NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Dumping data for table `gaminglaptops`
--

INSERT INTO `gaminglaptops` (`Category`) VALUES
('Gaming Laptops'),
('Electronics, PC Gaming, Gaming Computers'),
('Gaming Monitors'),
('Electronics, Television & Video, Televisions'),
('Electronics, Camera & Photo, Digital Cameras, DSLR Cameras'),
('Electronics, Accessories & Supplies, Audio & Video Accessories, TV Accessories & Parts, TV Ceiling & Wall Mounts'),
('Electronics, Accessories & Supplies, Audio & Video Accessories'),
('Electronics, Computers & Accessories, Monitors'),
('Electronics, Computers & Accessories, Computers & Tablets, Tablets'),
('Electronics, Computers & Accessories, Computers & Tablets, Laptops, 2 in 1 Laptops'),
('Electronics, Computers & Accessories, Computers & Tablets'),
('Electronics, Computers & Accessories, Computers & Tablets, Laptops, Traditional Laptops');

--
-- Indexes for dumped tables
--

--
-- Indexes for table `gaminglaptops`
--
ALTER TABLE `gaminglaptops`
 ADD PRIMARY KEY (`Id`),

You can change your query a bit to return unique results.

Use SUBSTRING_INDEX to extract 1st value,

SUBSTRING_INDEX('Electronics, PC Gaming, Gaming Computers', ',', 1)

will return Electronics.

Then do a distinct on your query,

SELECT DISTINCT(SUBSTRING_INDEX(`Category`, ',', 1)) AS Cat
FROM `laptops`
ORDER BY `Id`
DESC LIMIT 100

Now the query will return unique results with one value only. So, you can eliminate the need to explode the results in your loop. Optimized your snippet below,

<?php
while($row = mysqli_fetch_array($run_query_category)) 
?>
<li class="p-b-9">
 <a href="#" class="s-text7"><?php echo $row["Cat"]; ?></a>
</li>
<?php 

try with continue statement

<ul class="p-b-54">
 <li class="p-t-4">
 <a href="#" class="s-text13 active1">
 All
 </a>
 </li>
 <?php 
 $cat_name = "";
 $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops` ORDER BY `Id` DESC LIMIT 100 ";
 $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
 if(mysqli_num_rows($run_query_category) > 0)
 while($row = mysqli_fetch_array($run_query_category))
 $product_Category = $row["Category"]; 
 ?>

 <li class="p-b-9">
 <a href="#" class="s-text7">
 <?php 
 $prod_Cat = explode(", ", $product_Category);
 if($cat_name == $prod_Cat[0])
 continue;
 else
 $catname = $prod_Cat[0];
 
 echo $catname;
 ?>
 </a>
 </li>
<?php 
 
 
?>
</ul>

The simplest approached would probably be to create an empty array (such as $uniqueElements), iterate each of your elements in a for-loop and push each unique item into your empty array by checking the content with in_array($element, $uniqueElements).

You should save all your first-words in an array instantiated at the start like

$first_categories = ;

And then, for the sake of simplicity, in each iteration you could just append the value to the array like

$first_categories = $prod_Cat[0];

And get a new array with only the unique values

$unique_first_categories = array_unique($first_categories);

You can try saving it an array and check if exist

<ul class="p-b-54">
 <li class="p-t-4">
 <a href="#" class="s-text13 active1">
 All
 </a>
 </li>
 <?php 
 $cat_name = "";
 $allCat = array();
 $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops` ORDER BY `Id` DESC LIMIT 100 ";
 $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
 if(mysqli_num_rows($run_query_category) > 0)
 while($row = mysqli_fetch_array($run_query_category))
 $product_Category = $row["Category"];
 $prod_Cat = explode(", ", $product_Category);

 if(!in_array($prod_Cat[0], $allCats) // if not yet exist in array
 // push to allCats (unique)
 array_push($allCats, $prodCat[0]);
 // display
 ?>

 <li class="p-b-9">
 <a href="#" class="s-text7">
 <?php 
 echo end($allCats); // last item pushed
 ?>
 </a>
 </li>
 <?php 
 
 
 
 ?>
</ul>