What is the main issue the user is facing with converting an array from an SQL query into JSON format in PHP?

The main issue the user is facing is that the array from the SQL query needs to be properly encoded into JSON format in PHP. To solve this, the user can use the `json_encode()` function in PHP to convert the array into a JSON string.

// Assuming $result is the array from the SQL query
$json_data = json_encode($result);

// Output the JSON data
echo $json_data;