Talk:Check constraint
Add topicLatest comment: 4 years ago by 80.41.77.9 in topic UNKNOWN?
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[edit]Added links to this page from:
http://en.wikipedia.org/wiki/Update_%28SQL%29
http://en.wikipedia.org/wiki/Insert_%28SQL%29
http://en.wikipedia.org/wiki/SQL-92
http://en.wikipedia.org/wiki/Virtuoso_Universal_Server
This article currently has the following examples
- Some examples of dangerous constraints include:
- CHECK ((select count(*) from invoices where invoices.customerId = customerId) < 1000)
- CHECK (dateInserted = CURRENT_DATE)
- CHECK (countItems = RAND())
What is "dangerous" with these check constraints? --Abdull (talk) 15:34, 26 September 2012 (UTC)
UNKNOWN?
[edit]Why does this article refer to UNKNOWN? In SQL 'unknown' is represented by NULL, so surely this should say NULL? 80.41.77.9 (talk) 11:13, 16 August 2021 (UTC)