Using Aliases in same query

Alias is very helpful to shorten long query in SQL.

To use Alias in the same query you can use the following method:

SELECT  A,B,C*50 from (select A,B,(A+B) as C from table).

note that you can choose  any column from inner-query to display it in outer-query.

but you cannot display a column in outer-query which is not exist in inner-query.

You can try this example using SCOTT schema:

select  SAL,COMM,COMM_RATE *100 from (
select SAL,COMM,(COMM/SAL) as COMM_RATE from emp)

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