Databases Reference
In-Depth Information
• Once the set expression or state, has been constructed, play around and make
a few selections to see how each affects the calculation and ensure it's what
the user would expect.
• When you've arrived at a result using a set expression, replicate the base
expression, without the set portion, and try to arrive at the same result
using only selections. If everything is correct, the result should always be
the same, unless of course the modified record set cannot be replicated
using selections only.
Summary
We've come to the end of this chapter in which we've been able to use some
advanced expression techniques and Set Analysis to build period-over-period
comparisons. We have learned the syntax and variations of a set expression.
We also learned how to construct and use Set Analysis expressions to enable time
period comparisons, and also how to use some time-saving techniques to re-use set
expressions across different documents.
Finally, we learned how to use alternate states for comparative analysis.
Let's now move on to the next chapter, which expands on the concept of data
transformation at an advanced level.
