Hi

Somehow I get out of ideas!
I have a table on sheet Normatives:
ArticleNo ValidFrom ValidTo Normative
(CharNum) (Date) (Date) (Time)

The article column uses data validation, so I can't restrict there anything.
But I want to limit entries into columns ValidFrom and ValidTo and Normative
columns.
1. When ArticleNo is empty, no entries into ValidTo or ValidFrom is allowed;
2. When ValidFrom is empty, no entry into ValidTo is allowed;
3. ValidTo is always = ValidFrom, or empty. The last means, that the
normative is valid now (when ValidFrom is not empty), or that the normative
isn't determined (when ValidFrom is empty);
4. When same ArticleNo exist in table, an entry into ValidFrom is allowed
only, when for all other instances of article, ValidTo is not empty (all
other normatives must be 'closed');
6. When entering a new value into ValidFrom, it must not fall into any
ValidFrom-ValidTo date interval for other instances of same article (when
there is empty ValidTo with non-empty ValidFrom present, then ValidTo is
counted as TODAY());
7. The same as p.6 for ValidTo
8. No entry into Normative is allowed, until there is some non-empty value
in ValidFrom, and there is only one empty ValidTo, for this article.

To make it short - no overlaying normative intervals are allowed for same
article.

--
When sending mail, use address arvil<attarkon.ee
Arvi Laanemets