SQL Server : find members from a number - sql-server-2012

Question

Problem : How to find out from the given number from which numbers this number consists?
"Sunday = 1", "Monday = 2", "Tuesday = 4", Wednesday = 8", "Thursday =
16", "Friday = 32", "Saturday = 64"
For example : Given the number 109 this would signify Sunday, Tuesday, Wednesday, Friday, Saturday

Answer 1

You can do something like this.
CREATE FUNCTION dbo.Int2BinaryToWeekDay (#i INT) RETURNS NVARCHAR(2048) AS BEGIN
RETURN
CASE WHEN CONVERT(VARCHAR(16), #i & 64 ) > 0 THEN 'Saturday,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 32 ) > 0 THEN 'Friday,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 16 ) > 0 THEN 'Thurday,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 8 ) > 0 THEN 'Wed,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 4 ) > 0 THEN 'Tuesday,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 2 ) > 0 THEN 'Monday,' ELSE '' END +
CASE WHEN CONVERT(VARCHAR(16), #i & 1 ) > 0 THEN 'Sunday,' ELSE '' END
END;
GO
Now do following thing.
SELECT dbo.Int2BinaryToWeekDay(109)

Answer 2

Looks like a binary design. You need to use bitwise & operator to get the desired output.
Decimal = Binary
109 = 1101101
001 = 0000001
------&------
0000001 = 1
109 = 1101101
002 = 0000010
------&------
0000000 = 0
109 = 1101101
004 = 0000100
------&------
0000100 = 4
SQL Server has bitwise operators in built. you can utilize bitwise & for this like:
DECLARE #InputNum INT = 109
SELECT ISNULL(STUFF(CASE WHEN #InputNum & 1 > 0 THEN ', SUN' ELSE '' END +
CASE WHEN #InputNum & 2 > 0 THEN ', MON' ELSE '' END +
CASE WHEN #InputNum & 4 > 0 THEN ', TUE' ELSE '' END +
CASE WHEN #InputNum & 8 > 0 THEN ', WED' ELSE '' END +
CASE WHEN #InputNum & 16 > 0 THEN ', THU' ELSE '' END +
CASE WHEN #InputNum & 32 > 0 THEN ', FRI' ELSE '' END +
CASE WHEN #InputNum & 64 > 0 THEN ', SAT' ELSE '' END,1,2,''),'')
check the MS documentation for more detailed explaination of bitwise operators.