Stored vs unstored calculations

Classic Servoy
1

Anyone care to explain when I should use stored or unstored calculations. What are the pro’s and cons…I know people who preffer not to use calculations at all but prefer to calculate via a method when something is shown on the form.

The first rule of thumb I can find is to use stored calculations if you want to search on them. Are there any other rules?

2

tweetie:
Anyone care to explain when I should use stored or unstored calculations. What are the pro’s and cons…I know people who preffer not to use calculations at all but prefer to calculate via a method when something is shown on the form.

The first rule of thumb I can find is to use stored calculations if you want to search on them. Are there any other rules?

Storing your calc will affect your db structure (because you need a column).
So, if you need to search, summarize, do SQL etc on this field, you need to store the data.

3

Standard database structure says your database should store only data, not knowledge. For example, store someone’s birthdate, but do not store their age. That can be calculated when needed.
However, like Riccardino mentioned, if users want to search on one of those calculations, it may be faster to store them. It really all depends on database structure and usage.

4

Let me elaborate some more.
I allready knew that the data in a stored calculation would be stuffed into a column of table.

Suppose you have a date-column for valid_untill.
I want to warn someone with the following calculation (dont mind the syntax)

if (valid_untill<today)
  { return 'Warning';}
else
  { return 'Everything is cool';}

Would you use an unstored calculation, or would you use a method combined with an onRecordSelect to fill out a label?