Steve Jones - SSC Editor (1/20/2011)

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The NULL mistake is that people often write

where a.col = null

instead of

where a.col is null

Koen (da-zero) (1/20/2011)

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I would go to a session like this one.
I'm always eager to learn from more experienced people who have already learned from mistakes, so that I can avoid them

One question: what is wrong with IS NULL?

Steve Jones - SSC Editor (1/20/2011)

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The NULL mistake is that people often write

where a.col = null

instead of

where a.col is null

The multi-row trigger is the same. Developers assume triggers fire once per row, instead of once per transaction. I have examples of why this is an issue.

Steve Jones - SSC Editor (1/21/2011)

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Good point. I'll change the wording to say what the mistake is. Do you think

- writing single row triggers

or

- not coding triggers for multiple rows

is better?

Michael Valentine Jones (1/21/2011)

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I think the big mistake that beginners make with triggers is using them at all. They see them as a sort of event driven solution, and don't really understand the implications.

Triggers are kind of a bad practice of first choice for beginners, while experienced developers avoid them whenever possible.