Technology Tales

ERROR: Ambiguous reference, column xx is in more than one table.

5^th May 2012

Sometimes, SAS messages are not all that they seem, and a number of them are issued from PROC SQL when something goes awry with your code. In fact, I got a message like the above when ordering the results of the join using a variable that didn't exist in either of the datasets that were joined. This type of thing has been around for a while (I have been using SAS since version 6.11, and it was there then) and it amazes me that we haven't seen a better message in more recent versions of SAS; it was SAS 9.2 where I saw it most recently.

proc sql noprint;
    select a.yy, a.yyy, b.zz
        from a left join b
            on a.yy=b.yy
                order by xx;
quit;