Hey @dakkineni ,
As far as I understand, you will be able to get hold of your raw event data irrespective of how you send your events to Amplitude. There are several ways of querying your Amplitude event data with SQL :

• If you are a paid customer, then you can setup recurring exports to the cloud destination of your choice ( S3, Snowflake, GCS ) directly from the Amplitude UI.
• If you are not on a paid plan, then you can also leverage the Export API and create your own custom ETL pipeline. 
• There is also the Query add-on feature which allows you to query raw data via a Amplitude-managed Snowflake database.

Can you elaborate more on your 2nd question? Are you trying to join raw event data in an external warehouse or something you want to do inside Amplitude?

Hi Dakkineni,

Thanks for contacting Amplitude Support! Denis here and happy to shed some light on the situation!

Can I use sql to query data in Amplitude events, the ones that are HTTP kind of events that are streamed using Segment?
At the moment, the only way to perform SQL like queries within Amplitude would be via the Query and Snowflake add-on which is available for purchase to our Growth and Enterprise customers! If you would like me to connect you to our sales team, I'd be happy to assist.
You can read a bit about this feature here: https://help.amplitude.com/hc/en-us/articles/115001902492

Otherwise, if you're able to export your data via the export API and pass it into a system that can manage SQL queries then that would work as well!

I have two events with different columns and want to join these two events into a custom event based on key columns, how can I achieve this. If I don’t do a join the event data is displayed with blanks on each side where the column doesn’t exist in the breakdown table
Would you be so kind as to elaborate on what you mean here? Have you got a few user examples to show me what you mean or a simple mock up in text? I am just not entirely sure of what you mean by joining. We do have custom events where two or more events are put under one event and where you can specify properties for them. Is this what you were looking for? if not, could you please elaborate on what you are trying to achieve? Thank you!