because this is only a basic research. I want to build a view with more than 40 collumns and the most of these are based on a other column of these view.
The main resaon to do it on this wa is that I want to write each formula in the view only once.
I Think this is one way to implement that, but no sollution for my special problem. What is when a result called SOURCE3 is based by a formula on SOURCE2 ... an so on.. its like hierarchical formulas..
DBMS systems are not able to analyse math formula dependencies. In my point of view the dependencies must be described by subsubsubSelects ...
I think a well dbms must handle this :
SELECT SQR(C1) * -1 AS "C2" , ABS( COL ) * 5 AS "C1" , C2 -5 AS C3 FROM ...
You are right, SQL can't do that. The SQL SELECT clause can only look "down" into values from the tables and views in the FROM clause, it cannot look "across" to other values in the same SELECT clause. That's just the way it is.
The "select from select" approach is the way around it; why do you say it is no solution for you? You mean you just don't like it?