Re: count the number of bits set to 1 in a bit string field

Hi,

I don't quite know what you mean by a "bit string field" but for any
numeric, better integer row can use the following construct:

Say the bits you where testing where bit 3 ('00000100' bit),
 and bit 6 ('00100000' bit) of say some_integer row....

then this would do it:

select
 sum(case when (some_int & x'0004'::int)=0 then 0 else 1 end)
  as count_of3thbit,
 sum(case when (some_int & x'0020'::int)=0 then 0 else 1 end)
  as count_of6thbit
from mytable ;

 constant x'0004'::int = 4
 constant x'0020'::int = 32


by best regards,



Stefan


Am Sonntag, 15. Juli 2007 21:35 schrieb Rajarshi Guha:
> Hi, is there a built in function that will give me the number of bits
> that are set to 1 in a bit string field?
>
> Thanks,
>
> -------------------------------------------------------------------
> Rajarshi Guha  <rguha@indiana.edu>
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