a week ago
Relates to all questions:
Provide examples of what you mean. Subject title should be descriptive of the problem etc.
a week ago
How to tell a compiler error from execution error
Do you mean by "compiler error" that the compiler made an error or that the compiler detected a programming syntax error? If the last then checking the log for errors. If you have fatal syntax error SAS is usually pretty good with showing where the first error occurs. Often that error will cause others such as "data set not found" because the step that was to create the set failed.
Basically "check the log" and read the error and warnings.
There are so many ways for users to make logic errors there isn't any one way to tell execution errors though running code on data where you "know" what the results should be is common. Of course assuming your variables are numeric when the values are actually character, or vice versa, often results in unexpected results. But that is because you did not actually "know your data".