Obtaining comma-separated list of text values associated with bitwise flag column

Question

In the table msdb.dbo.sysjobsteps, there is a [flags] column, which is a bit array with the following possible values:
0: Overwrite output file
2: Append to output file
4: Write Transact-SQL job step output to step history
8: Write log to table (overwrite existing history)
16: Write log to table (append to existing history)
32: Include step output in history
64: Create a Windows event to use as a signal for the Cmd jobstep to abort
I want to display a comma-separated list of the text values for a row. For example, if [flags] = 12, I want to display 'Write Transact-SQL job step output to step history, Write log to table (overwrite existing history)'.
What is the most efficient way to accomplish this?

Answer 1

Here is a query that gives the pattern:
DECLARE @val int = 43
;WITH numbers AS (
   SELECT power(2, n) AS exp2 FROM (VALUES(0), (1), (2), (3), (4), (5), (6)) AS n(n)
), list(list) AS (
   SELECT
     (SELECT CASE WHEN exp2 = 1  THEN 'First flag'
                  WHEN exp2 = 2  THEN 'Flag 2'
                  WHEN exp2 = 4  THEN 'Third flag'
                  WHEN exp2 = 8  THEN 'IV Flag'
                  WHEN exp2 = 16 THEN 'Flag #5'
                  WHEN exp2 = 32 THEN 'Another flag'
                  WHEN exp2 = 64 THEN 'My lucky flag'
             END + ', '
      FROM   numbers
      WHERE  exp2 & @val = exp2
      ORDER BY exp2
      FOR XML PATH(''), TYPE).value('.', 'nvarchar(MAX)')
SELECT substring(list, 1, len(list) - 1)
FROM   list
Here I'm creating the numbers on the fly, but it is better to have a table of numbers in your database. It can be used in many places, see here for a short discussion:
http://www.sommarskog.se/arrays-in-sql-2005.html#numbersasconcept
(Only read down to the next header.)
For FOR XML PATH thing is the somewhat obscure way we create concatenated lists. There is not really any using trying to explain how it works; it just works. The one thing to keep in mind is that it adds an extra comma at the end and the final query strips
it off.
This query does not handle that 0 has a special meaning - that is left as an exercise to the reader.
Erland Sommarskog, SQL Server MVP, [email protected]