Feedback Option in Proc SQL

[priyankachauhan]

Feedback option in proc sql statement we use to display columns in logs. so what is use of it?There is any benefit to see columns in log files.

[AllanBowe]

It's one of a number of tools that can be useful in debugging and tracing data lineage.  It doesn't just display columns - it also expands any VIEWS to help further with understanding the underlying execution operations.  For regular, stable, production jobs - it's probably not helpful.

For debugging that one job, that was written 15 years ago by somebody who has now disappeared - priceless.

There's a great paper on it here:  http://analytics.ncsu.edu/sesug/2012/CT-05.pdf

[Reeza]

Yes, it's helpful for the lazy programmer like me. 
I often use FEEDBACK to expand the * list out to a full set of variables with the appropriate alias and then manually select out the variables I want. So I use it as a code generation tool. You won't see it in PROD code because I only use it for development, but that's just a single example. 

proc sql feedback;
create table want as
select * , '1' as union_join
from sashelp.class
union
select * , '2' as union_join
from sashelp.air;
quit;