Convert integer to a list of week days

Question

I have an integer stored in a database (SQLAgent Frequency Interval) This integer is actually the sum of the selected days of the week that the schedule is to run The possible v

Answer 1

I would start by putting it on an user defined function. Also, you can use an and that operates at the bit level to check for it - I think it is &, will update.

Update 1: It was &, Jason already put up an example. I still recommend to use an user defined function for it :).

Answer 2

DECLARE @in INTEGER;
SET @in = 63;
WITH series(n) AS
    (
    SELECT  0
    UNION ALL
    SELECT  n + 1
    FROM    series
    WHERE   n < 6
    )
SELECT  CASE WHEN ROW_NUMBER() OVER (ORDER BY n) > 1 THEN ', ' ELSE '' END + DATENAME(weekday, DATEADD(day, n, '1980-09-03')) 
FROM    series
WHERE   (POWER(2, n) & @in) > 0
ORDER BY n
FOR XML PATH ('')

Answer 3

Edit: This is C# code to do the bit operations. I posted it before reading the question in detail, but I will leave it here as an alternative. Is the database really the best place to do this...?

You can use an array:

// input: int value
string[] weekdays = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Saturday" };
int flag = 1
List<string> days = new List<string>();
foreach (string day in days) {
   if ((value && flag) != 0) {
      days.Add(day);
   }
   flag <<= 1;
}

The result is a list of strings, if you want to merge them you can for example do:

string selected = String.Join(", ", days.ToArray());

Answer 4

You can use bit-wise operators in T-SQL. Here's how:

SELECT
  ( CASE WHEN daybits & 1 = 1 THEN 'Sunday ' ELSE '' END ) +
  ( CASE WHEN daybits & 2 = 2 THEN 'Monday ' ELSE '' END ) +
  ( CASE WHEN daybits & 4 = 4 THEN 'Tuesday ' ELSE '' END ) +
  ...
  ( CASE WHEN daybits & 64 = 64 THEN 'Saturday ' ELSE '' END ) +

That will produce "Sunday Saturday" for example.