Can we put SQL query output to csv file?

Local Setup
1

Query like
select email from users where email!=‘NULL’;

into local csv file

2

@Raja_Nukala I think the query you want looks like:

SELECT email FROM users WHERE email <> NULL;

Why do you want to export all users who have an email address to a CSV?

3

i want to send newsletters to all emails.

4

The easiest way to solve this task is to write an RPC function you can call with the HTTP key which will execute a custom SQL query that looks like:

SELECT json_agg(row) AS emails FROM (SELECT email FROM users WHERE email <> NULL OR email <> '') AS row;

The output of the query will look similar to:

                 emails                  
-----------------------------------------
 [{"email":"abc@gmail.com"}, +
  {"email":"xyz@yahoo.co.uk"}]
(1 row)

You can run this custom SQL within a small RPC function that would send the results back as a JSON object. Have a look at the server framework function reference for how to achieve it:

https://heroiclabs.com/docs/runtime-code-function-reference/#sql