On 2022-06-17 17:14:14 -0700, Bryn Llewellyn wrote: > "isbn" — string > values must be unique across the entire set of documents (in other words, it > defines the unique business key); values must have this pattern: > > « ^[0-9]{3}-[0-9]{1}-[0-9]{2}-[0-9]{6}-[0-9]{1}$ » Completely off-topic, but this regexp doesn't describe ISBNs. In ISBNs the three middle subfields are all variable length. The first is a language code (there are more than 10 languages in the world), the second identifies the publisher (there are more than 100 publishers) and the third the book. For example, "Mastering PostgreSQL 9.6" has the ISBN 978-1-78355-535-2. hp -- _ | Peter J. Holzer | Story must make more sense than reality. |_|_) | | | | | hjp@xxxxxx | -- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!"
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