Questions tagged [celko]
2 questions
10
votes
2 answers
SQL Server: Why does comparison null=value return true for NOT IN?
Why does the comparison of value to null return false, except when using a NOT IN, where it returns true?
Given a query to find all stackoverflow users who have a post:
SELECT * FROM Users
WHERE UserID IN (SELECT UserID FROM Posts)
This works as…
Ian Boyd
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2
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2 answers
querying tree/graphs modeled in SQL (Celko)
Do you know any reference where to find SQL queries for traversing trees/graphs?
I found this one: http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html and Celko's book.
Problem is that the majority of resources I found refers to…
Daniele
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