Conditionally skip transformations in SAS DIS

Question

I am wondering if it is possible to use a Conditional Start transformation in SAS DIS to conditionally bypass another transformation based on whether a given table is empty (no rows). This link seems to indicate that the condition must be based on the value of a parameter variable.

One idea I had was to create a parameter value in a User Written Code transformation, and assign it different values depending on the state of the table, but this seems elaborate and inelegant, and I'm not sure that it would work. Is there a simpler way?

Much gratitude

Answer 1

The original question asked how to tell if a table did not exist at all, and this answer solves that problem. It does not help tell if a dataset has zero rows.

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Since your link says that it will simply %eval whatever you put in that box, you may be able to use the exist function.

For example:

%put %sysfunc(exist(sashelp.class));
%put %sysfunc(exist(sashelp.classzas));

The first returns 1 (true), the latter 0 (false) on my machine.

Answer 2

To get this done without adding any user written transformation and perhaps elegantly you can try what i generally use. First, copy the numobs macro posted by @cmjohns ( https://stackoverflow.com/a/5664379/4653284 ) and add it to the precode of the jobflow. After that go to the starting transformation which needs to be skipped based on the observation and right click to get properties tab of that transformation. Then goto the "Precode and Postcode" tab and add the following code:

%macro dummy;
%if %nobs(&SYSLAST) gt 0 %then %do;

After that is done, goto the transformation which would be the last transformation to be skipped basis the observation count and right click to get properties of the transformation and goto Precode Postcode tab and add the following code:

%end;
%mend dummy;
%dummy;

If only 1 transformation needs to be skipped then you can add the post code and precode provided above in the same precode and post code tab of that single transformation to skip it based on observation count.

Note: SAS DI Studio 4.8 has Conditional Transformations which can solve the same problem. But for DI studio version before that we have to code to get the conditional exclusion of transformation(s).