Month: September 2006

The prime number challenge – great waste of time!

No sane person would even consider using SQL Server to construct a list of prime numbers. So just to prove that I’m not sane (as if there could be any doubt!), this post will be about finding prime numbers.   First a bit of history. Ward Pond wrote about efficient ways to populate a table with one million GUIDs. I posted a comment with a slightly more efficient algorithm. And that was quickly followed by a new post from Ward, tweaking my syntax even further. And that’s when Denis the SQL Menace lived true to his name by posting this…

Snapshot isolation: A threat for integrity? (Part 4)

In the previous parts of this series, I have shown how SQL Server prevents violations of foreign key constraints by silently disabling snapshot isolation. I have also demonstrated how you can use the same technique inside your trigger code, to keep snapshot isolation from damaging your custom integrity rules. Now, in the final part of this series, I will investigate some less common techniques for preserving integrity. Note that I would normally not recommend any of these techniques, but I do see them often enough in newsgroup postings. Apparently, they are used.   First, I’ll set up the tables again.…

Fun with ambiguous table names

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Earlier today, I realised that Microsoft has forgotten to include some keywords in the list of reserved keywords. Now, a wise developer will still take care to omit those names when naming tables – but a bored developer can have loads of fun exploring the effects!   The keywords I am referring to are inserted and deleted. Everyone who ever coded a trigger knows that they refer to the pseudo-tables that hold the before and after image of all rows affected by the triggering DML statement. But since they’re not reserved keywords, it’s perfectly legal to name a column “inserted”.…

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