Select all columns with specific value - sql

Question

I have a table that has around 200 different boolean columns. These are basically On/Off switches used to blacklist data in another application. This also has multiple rows for different functionalities within said application.
As you can imagine, keeping a good overview over which columns are "turned on" for a specific function is rather tiresome when you have to manually check them against some excel sheet, so I want to make my life easier by only displaying columns that are turned on/set to true.
Something like:
select [columns with value '1']
from table
where function = 'function1'
Where this table:
+-----------+------+------+------+------+------+
| function | Col1 | Col2 | Col3 | Col4 | Col5 |
+-----------+------+------+------+------+------+
| function1 | 1 | 0 | 1 | 1 | 0 |
| function2 | 0 | 1 | 0 | 0 | 0 |
+-----------+------+------+------+------+------+
returns this:
+----------+------+-------+-----+
| function | Col1 | Col3 | Col4 |
+-----------+------+------+------+
| function1 | 1 | 1 | 1 |
+-----------+------+------+------+
Is there any way to do something like this?

Answer 1

As is mentioned in the comments, result columns are defined independent of table data, but the following approach, which returns the columns names as a single column, is a possible solution:
Table:
CREATE TABLE Data (
[Function] varchar(3),
Col1 bit,
Col2 bit,
Col3 bit,
Col4 bit,
Col5 bit
)
INSERT INTO Data ([Function], Col1, Col2, Col3, Col4, Col5)
VALUES ('xyz', 1, 0, 1, 1, 1), ('abc', 0, 0, 0, 0, 1)
Dynamic statement:
DECLARE #stm nvarchar(max) = N''
SELECT #stm = CONCAT(#stm, ',(','''', col.[name], ''', ', col.[name], ')')
FROM sys.columns col
JOIN sys.tables tab ON col.object_id = tab.object_id
JOIN sys.schemas sch ON tab.schema_id = sch.schema_id
JOIN sys.types typ ON col.system_type_id = typ.system_type_id
WHERE
tab.[name] = 'Data' AND
sch.[name] = 'dbo' AND
col.[name] != 'Function'
ORDER By col.[name]
SELECT #stm = CONCAT(
'SELECT d.[Function], STRING_AGG(v.ColName, '','') AS [Columns] FROM Data d CROSS APPLY (VALUES ',
STUFF(#stm, 1, 1, ''),
') v(ColName, ColVal) WHERE v.ColVal = 1 GROUP BY d.[Function]'
)
PRINT #stm
EXEC sp_executesql #stm
Result:
Function Columns
abc Col5
xyz Col1,Col3,Col4,Col5

Answer 2

This is an example, I hope it helps, it's a little tricky, but gets what you want, at least could it helps to your progress, if you have any doubts send me a message or comment, good luck.
IF OBJECT_ID('dbo.TestMr') IS NOT NULL DROP TABLE TestMr
IF OBJECT_ID('tempdb.dbo.#TestMrColumns') IS NOT NULL DROP TABLE #TestMrColumns
CREATE TABLE TestMr(x_function varchar(50),col1 numeric, col2 numeric, col3 numeric)
CREATE TABLE #TestMrColumns(y_function varchar(50),valor varchar(50),columna varchar(50))
--TEST VALUES
INSERT INTO TestMr VALUES('fun1',1,0,1)
INSERT INTO TestMr VALUES('fun2',0,1,0)
DECLARE #script nvarchar(max)
DECLARE #cols nvarchar(max)
--We get the columns from our table, this columns have to be of the same data_type or this wont work.
SET #cols = STUFF((SELECT ',' + QUOTENAME(COLUMN_NAME) FROM INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='TestMr' and DATA_TYPE='numeric' FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)'),1,1,'')
--we make that columns rows to save them on a tempTable
set #script='select * from TestMr unpivot(valor for columna in ('+#cols+')) unpiv'
insert into #TestMrColumns exec (#script);
--we get the final columns for our select, here we can apply conditions for the columns that we want, in this case, we get
--the columns that had valor=1 and y_function=fun1/
SET #cols = STUFF((SELECT ',' + QUOTENAME(columna) FROM #TestMrColumns where valor=1 and y_function='fun1' FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)'),1,1,'')
--final select
set #script='select x_function,'+#cols+' from TestMr where x_function=''fun1'' '
exec(#script)