有没有更好的方法在PHP中编写folling代码

Question

I am trying to write a function that will fetch one column from mysql & return it. some how I am not able to write get_hash() function. Further is it safe to use $GLOBALS?

<?php
    //Create Database Connection 
    $dbhost = "localhost";
    $dbuser = "developer";
    $dbpass = "abc";
    $dbname = "abc";
    $connection = mysqli_connect($dbhost,$dbuser,$dbpass,$dbname);

    //Test Connection`enter code here`
    if(mysqli_connect_errno()) {
        die("Connection Failed" . 
            mysqli_connect_error() . 
            "(" . mysqli_connect_errorno() . ")"
        );  
    }

    // Query
    $query = "SELECT tweet FROM twc_hashtag";


    // Fetch Data
    function get_hash() {   
        if ($result=mysqli_query($GLOBALS['connection'], $GLOBALS['query'])){  

                while ($row=mysqli_fetch_row($result)){
                    //echo "<tr>";
                    //echo "<td>" . $row[0] . "</td>";
                    //echo "</tr>";
                    return $row[0];
                }   
            }

        //Test Query Error
        if(!$result){
            die("Database Query Failed" . mysqli_error($GLOBALS['connection'])); 
        }   

    }


    //Close The Connection
    mysqli_close($connection);

?> 

I need to fetch the data in a different php file & then pass that data to a javascript function. Hence I am going to call get_hash(); from a different php file.