Reference link:
1 https://stackoverflow.com/questions/40650747/uncaught-error-call-to-undefined-function-mysql-select-db
The solutions are as follows:

<?php  
$username="root";  
$password="namungoona";  
$hostname = "localhost";  
//connection string with database  
$dbhandle = mysqli_connect($hostname, $username, $password)  
or die("Unable to connect to MySQL");  
echo "";  
// connect with database  
$selected = mysqli_select_db($dbhandle, "police")  
or die("Could not select examples");  
//query fire  
$result = mysqli_query($dbhandle,"select * from News;");  
$json_response = array();  
// fetch data in array format  
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {  
// Fetch data of Fname Column and store in array of row_array
$row_array['Headlines'] = $row['Headlines'];  
$row_array['Details'] = $row['Details']; 
$row_array['NewsPhoto'] = $row['NewsPhoto']; 

//push the values in the array  
array_push($json_response,$row_array);  
}  
//  
echo json_encode($json_response); 
mysqli_free_result($result);
?>