PL/SQL Logical Operators evaluate whole function

Question

I know in C like languages logical operators are evaluated one at a time so:

false && really_expensive_function()

is doesn't result in the function being called (I can't remember the CS name for this). Does the same happen in PL/SQL or do I need to break the IF parts out to separate blocks?

ChristopheD · Accepted Answer · 2010-03-09T12:06:06.380

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The CS name is short-circuiting (wikipedia entry on short-circuit evaluation) and yes, plsql does exactly that.

edited Mar 09 '10 at 12:06

answered Mar 09 '10 at 11:26

ChristopheD

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Ace cheers - you never know with some of the crazy things in the world of PL/SQL – Chris Mar 09 '10 at 11:36
@Chris: That's true :) Have a look at this one for example: http://stackoverflow.com/questions/2021140/why-does-nvl-always-evaluate-2nd-parameter – Peter Lang Mar 09 '10 at 11:37
+1 Maybe you should update your answer to say "does" rather than "should" to dispel any doubt! – Tony Andrews Mar 09 '10 at 12:05
@Chris, @Tony Andrews: thanks, I've updated the answer to avoid possible confusion. – ChristopheD Mar 09 '10 at 12:06

score 0 · Answer 2 · edited May 23 '17 at 12:18

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I think the term you are looking for is "lazy evaluation". You may want to look at this question.

edited May 23 '17 at 12:18

Community

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answered Mar 09 '10 at 11:27

Klaus Byskov Pedersen

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PL/SQL Logical Operators evaluate whole function

2 Answers2