AND/OR operators, no parentheses

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Viktoria asked Jul 19, '10

AND/OR operators, no parentheses

Hello, I am trying to read this where clause, wondering if I am reading it right: [START_DATE] <= EFFDAT AND END_DATE > EFFDAT OR [START_DATE] <= EXPDAT AND (EFFDAT != EXPDAT) Would you say that this means this: ([START_DATE] <= EFFDAT AND END_DATE > EFFDAT) OR ([START_DATE] <= EXPDAT AND EFFDAT != EXPDAT) OR THIS: ([START_DATE] <= EFFDAT AND END_DATE > EFFDAT) OR ([START_DATE] <= EXPDAT) AND (EFFDAT != EXPDAT) Thanks so much!

operator or parentheses and no

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Answer 1 · 2010-07-19T09:39:51Z

Kev Riley answered Jul 19, '10

Without parentheses the operators follow the rules of [Operator Precedence][1], which puts the AND before the OR, so will read ( [START_DATE] <= EFFDAT AND END_DATE > EFFDAT ) OR ( [START_DATE] <= EXPDAT AND (EFFDAT != EXPDAT) ) However as you have seen it is better for human readability to always include the parentheses [1]: http://msdn.microsoft.com/en-us/library/ms190276.aspx

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Answer 2 · 2010-07-19T09:40:57Z

Oleg answered Jul 19, '10

The first one reflects the meaning because logical **AND** has a precedence over **OR**. That said, it is just plain evel not to segregate the statements with parentheses in order to make the intentions clear. Here is the BOL link: [ http://msdn.microsoft.com/en-us/library/ms186992.aspx][1] Oleg [1]: http://msdn.microsoft.com/en-us/library/ms186992.aspx

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Answer 3 · 2010-07-19T09:41:37Z

Viktoria answered Jul 19, '10

Thank you very much!

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Kev Riley ♦♦ commented · Jul 20, 2010 at 01:24 AM

@Viktoria : if an answer helps you please show this by accepting the answer (click the tick next to the answer you like)

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Oleg commented · Jul 20, 2010 at 01:22 PM

@Kev Riley Actually, she should probably accept your answer because:

1. I answered later than you
2. My answer happens to be a replica of yours (not intended).
3. I disgracefully misspelled the word evil.

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Viktoria commented · Jul 20, 2010 at 01:43 PM

Both comments were very helpful. Thank you!

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Oleg commented · Jul 20, 2010 at 02:11 PM

@Viktoria Thank you, but could you please mark Kevan's answer as accepted? (click the tick next to his answer). You are the only one who can do it because this is your question (other people don't see 'Accept' box). This allows other users of the site to find the answers quicker.

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