MYSQL导航栏将类别添加到类别表但检查类别是否已存在

Question

I made a navigation bar where I store my menus on my webpage.

I created a table for it called categories, and I managed to add a category to it via a button. I can add everything to it, but if I add something to it, I want to check if it already exists in the categories table. If it does, then echo 'already exists`. If not, insert the data.

I can't solve this. Thanks for the help.

<?php

function addCategory(){
      if(isset($_POST['submit'])){
          global $connection;
          $cat_title = $_POST['cat_title']; 

          if($cat_title == "" || empty($cat_title)){
              echo "this cannot be blank";
          } else {                            
              $query="INSERT INTO categories(cat_title)";// ADD CATEGORIES IN CATEGORIES.PHP //
              $query .= "VALUES ('$cat_title')";
              $result = mysqli_query($connection,$query);

              if(!$result){
                 die('Query failed' . mysqli_error);
              }

          }  
     }
} 

?>

Answer 1

CREATE UNIQUE INDEX cat_title_index ON categories (cat_title)

This made my problem solved :)