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Question : How do I count the number of set flags in a bitmask?
I know how to use bitwise operators to determine whether a particular bit is set or not. eg: to check if the third bit is set I might say (in psuedo code)
if myBitMask & 4 = 4 then TRUE
however, I have a bitmask of 2,000 bits, and i want count how many are set (the set bits represent a bad event occured, and i want to count how many bad events occurred in total.
eg:
00001000011100000001000000
100001 should be "7"
i.e in pseudo code: countofSetFlags(myBitMask)
I'm hoping to do this efficiently. I'll be querying over a million rows,
Thanks !!!
Paul
Answer : How do I count the number of set flags in a bitmask?
what data type is the field for the bitmask?
if it is varchar, just do this:
len(replace(yourfield, '0',''))
if it's not varchar, just cast it to varchar, and apply the above expression
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