PHP createdatabase if not exists is not working

While trying to create a database if not exists, I encountered the following errors, my code can be seen below. It is in two files, the createDatabase.php and the connectionDB.php.

it is showing me this error below:

Fatal error: Uncaught mysqli_sql_exception: Unknown database ‘dictionary’ in
C:xampphtdocsdictionaryconfigcreateDatabase.php:8 Stack trace: #0
C:xampphtdocsdictionaryconfigcreateDatabase.php(8): mysqli_select_db(Object(mysqli),
‘dictionary’) #1 C:xampphtdocsdictionaryconfigcreateDatabase.php(28): checkIfDatabaseExist()
#2 {main} thrown in C:xampphtdocsdictionaryconfigcreateDatabase.php on line 8

createDatabase.php

    function checkIfDatabaseExist(){
        $servername = "localhost";
        $username = "root";
        $password = "";
        $dbname = "dictionary";
        $conn = mysqli_connect($servername,$username,$password);
        if(!mysqli_select_db($conn,$dbname)){
            $createDatabase = "CREATE DATABASE IF NOT EXISTS $dbname";
            mysqli_query($conn,$createDatabase);
        }
        mysqli_close($conn);
    } 
    function checkIfTableExist(){
        $servername = "localhost";
        $username = "root";
        $password = "";
        $dbname = "dictionary";
        $conn = mysqli_connect($servername,$username,$password,$dbname);
        $checkTable = "SELECT 1 FROM dictionary_resource LIMIT 1";
        $result = mysqli_query($conn, $checkTable);
        if($result){
            echo "exist";
        }else {
            echo "noExist";
        }
    }
    checkIfDatabaseExist();
    checkIfTableExist();
?>```


 connectionDB.php

 ``<?php
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "dictionary";
    $conn = mysqli_connect($servername,$username,$password,$dbname);
    if(!conn){
        die("Connection Failed: ".mysqli_connect_error());
    }
?>`