Binary "OR" operation on a SQL column - sql

Question

I have a query that returns weekdays
Select PERSON_NAME, PERSON_DAY from PERSON_DAYS WHERE PERSON_ID = #myId
say I obtain
John 1 (mo)
John 3 (mo tu)
John 8 (th)
I need to obtain for John all the days when is busy. How do I a logical OR on the PERSON_DAY column in this query?
the result should be 11 (mo tu th)

Answer 1

well here my best so far
;with PowersOf2
as
(
select 1 as Number
union all
select A.Number * 2 from PowersOf2 as A where A.Number < 64
)
select P.PERSON_NAME, sum(distinct P.PERSON_DAY & PowersOf2.Number)
from PERSON_DAYS as P
left outer join PowersOf2 on PowersOf2.Number <= P.PERSON_DAY
where P.PERSON_ID = #myId
group by P.PERSON_NAME
SQL FIDDLE EXAMPLE

Answer 2

If I understand you correctly, you can use a combination of bitwise operator and and aggregate function sum to do what you want.
Example:
with person_days as (
select 'John' as person_name, 1 as weekday --mo
union select 'John', 3 -- mo, tu
union select 'John', 8 -- th
union select 'Jane', 1 -- mo
union select 'Jane', 9 -- mo, th
union select 'Jane', 40 -- th, sa
),
Bits AS (
SELECT 1 AS BitMask --mo
UNION ALL SELECT 2 --tu
UNION ALL SELECT 4 --we
UNION ALL SELECT 8 --th
UNION ALL SELECT 16 --fr
UNION ALL SELECT 32 --sa
UNION ALL SELECT 64 --su
UNION ALL SELECT 128
)
, person_single_days as (
select distinct person_name, weekday & bits.BitMask single_weekday
from person_days
inner join bits on person_days.weekday & bits.BitMask > 0
)
select person_name, sum(single_weekday) weekdays
from person_single_days
group by person_name;
result:
person_name weekdays
----------- -----------
Jane 41
John 11

Answer 3

"inspired" by Roman's CTE: (note that the first CTE just generates demo data)
with p as
(
select 'John' as PERSON_NAME, 1 as PERSON_DAY
union
select 'John', 3
union
select 'John', 8
union
select 'Jane', 2
union
select 'Jane', 4
),
cte as
(
select PERSON_NAME, PERSON_DAY from p
union all
select cte2.PERSON_NAME, p.PERSON_DAY | cte2.PERSON_DAY
from p
inner join cte as cte2 on p.PERSON_NAME = cte2.PERSON_NAME
where p.PERSON_DAY & cte2.PERSON_DAY = 0
)
select PERSON_NAME, MAX(PERSON_DAY) from cte
group by PERSON_NAME

Answer 4

I think what you are looking for is a custom aggregate that does an OR. You can write that using SQL CLR in .NET. This is probably the cleanest solution. It will be reusable, too.
Alternatively, you could use cursor-based loops to calculate the result.
You could also (mis)use CTE's for this purpose.