Hi @gokulnath ,
You can download an install called SQL Management Studio which will allow you to connect to a SQL server and look at the tables and schema (provided you have access).
Alternatively, you can ask IT to see if they can provide any entity relationship diagrams or other artifacts.
I am assuming you are moving off SQL and onto SP due to the premium connector required for SQL? SharePoint will work for certain scenarios but there are also limitations especially searching/filtering and delegated queries for large datasets.
--------------------------------------------------------------------------
If I have answered your question, please mark my post as a solution
If you have found my response helpful, please give it a thumbs up
Connect on LinkedIn