In-line variable assignment 2

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In-line variable assignment 2

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stephen.long.1 SSCrazy Points: 2591 More actions · Answer 1

stephen.long.1

SSCrazy

Points: 2591

August 11, 2014 at 7:59 am

#1736872

Good question, thanks, Hugo.

Raghavendra Mudugal SSChampion Points: 10658 More actions · Answer 2

Thank you for the post, Hugo, good one.

(so simple... declaration takes precedence of value assignment, even though it is in-line)

ww; Raghu
--
The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.

Hugo Kornelis SSC Guru Points: 64790 More actions · Answer 3

Thanks, all, for the nice words!

Sektor / Iulian: Yes, this is indeed different from C#, which (as far as I know - probably not very far) uses multiple-pass compilation. T-SQL uses single-pass, and has very different scoping rules. As far as I know, that is indeed by design, though badly documented.

thokozanik (8/11/2014)
Hugo, I thought the reason why the answer is null is because the evaluation of IF 1 < 0 get returned as false

That is part of the explanation. Because 1 < 0 evaluates as false, the (implied) SET statement that gives @j-2 its value is never executed. (And neither is the SET that changes the value of @i, though that becomes irrelevant for the question once you realize why @j-2 is not initialized at all).

Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
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