Making the Mirror Clause Work
The great thing about working with the AN and ANH tables in Classic is that they are exact "mirrors" of each other.
The table layouts are exactly alike, unlike the PO and the POH tables. Because they are exactly alike, Cerner has provided a
means of reading either table automatically without having to use functions like "Decode" and "Orjoins" The way you do this, of
course, is with the "Mirror" function. The "Mirror" function is really pretty straight-forward and works quite well.
Unless you try to "Plan" on the AN and then your results get pretty strange.
The trick is to remember that you cannot use the "Mirror" function if the AN table is the first (or only) table in your
"Plan." For the "Mirror" function to work, you must "join to" the AN, not "join from" it.
So, what do you do if the AN is the only table you need or you must read it before you read any other table?
Meet the "Dummyt" table. This is perhaps the most versatile table in the entire system. It consists of a single record of 2 fields.
The first field is "User" just like the first field in every primary key of every Cerner table. Consequently, you can "plan on" the Dummyt and
"join to" the AN "where d.user=an.user1 and test_nbr=an.proc_nbr1, etc.