I want to edit some row values once I get a query output in the result grid. Its true that we can right click the table and say open table to get an editable table output, b
Yes, This is possible. Right click on the table and Click on Edit Top 200 Rows as show in image below

Then click anywhere inside the result grid, to enable SQL Icon "Show Sql Pane". This will open sql editor for the table you opted to edit, here you can write your own sql query and then you can directly edit the result set of the query.

If you need to frequently perform in-cell edits on SQL databases, HeidiSQL works a treat, couldn't be simpler to use, and is free / open source (donations accepted).
Originally written for MySQL, it can now handle SQL Server, and has experimental (as of Aug 2014) PostgreSQL support as well.