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I have a flag enum array that I create and store in the database with my program as a numeric value. Is there anyway with a Postgres function to check for whether or not a specific bit is set?

So it would be:

value1 = 1
value2 = 2
vaule3 = 4
....
value10 = 512

I want to check that 534 has the value2 flag. Is that possible?

Erwin Brandstetter
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Travis Lange
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1 Answers1

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Yes, there is the very convenient "bitwise AND" operator & for integer numbers:

SELECT 534 & value2 = value2;

When logically "anded" with a power of 2 the same power of 2 is returned if the bit is set. (Since every power of 2 is represented by a distinct bit in the binary representation of a positive integer number.) Else you get 0. Compare the result with the value itself and you get either TRUE or FALSE. Voilá.

Related:

Erwin Brandstetter
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  • That's awesome! That's so simple... I'm a little ashamed of myself for not being able to find that lol, I guess my terms used in google just didn't produce the results I needed. Thank you. – Travis Lange Feb 27 '18 at 15:01