Is it possible to give a query in the from clause

Question

Hi all Is it possible to give a sql query in the from clause befor the giving a table name. for instance:- select top 1 Salary from(select top 2 Salary from sstable order by Salary desc) aas it is working but my question is what is happening here Whether a table is created virtually in the name aas

Venkatesan Jayakantham · Answer

As specified by drishty the query select top 2 Salary from sstable order by Salary desc is a derived table. It will created temporarily in the memory and the second query will be executed on the result set of the derived table. Cheers Venkatesan Prabu .J http://venkattechnicalblog.blogspot.com/

DRISHTY · Answer

Hello Select query in from clause is called derived table. They are created on the fly and then use these derived tables within your query. In very basic terms a derived table is a virtual table that's calculated on the fly from a select statement. In concept this is similar to creating a temporary table and then using the temporary table in your query but the approach is much simpler because it can all be done in one step.