'select' +  @column + ' from table'

'select' +  @column + ' from table'

if @column  = 'column1' select column1 from table
else if @column  = 'column2' select column2 from table
...

DROP TABLE IF EXISTS dbo.tbl
GO

CREATE TABLE dbo.tbl (a INT, b INT, c INT, d INT)
GO

DROP TABLE IF EXISTS #t
SELECT [name] = ',' + [name]
INTO #t
FROM sys.columns
WHERE [object_id] = OBJECT_ID('dbo.tbl')

DECLARE @rn INT = @@rowcount

DROP TABLE IF EXISTS #variants

;WITH cte AS
(
    SELECT lvl = @rn, x = (
        SELECT [name]
        FROM #t
        FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)')

    UNION ALL

    SELECT t1.lvl - 1, REPLACE(t1.x, t2.[name], '')
    FROM cte t1
    CROSS APPLY #t t2
    WHERE t1.lvl > 1
)
SELECT DISTINCT x
INTO #variants
FROM cte

SELECT 'select ' + STUFF(x, 1, 1, '') + ' from dbo.tbl'
FROM #variants

create table #t(c varchar(100), d date)


insert #t(c, d)
select 'blalba', getdate()


select choose(1, c, d) from #t

create table #t(c varchar(100), d date)


insert #t(c, d)
select 'blalba', getdate()

; with a as (
select	
	c = choose(1, cast(c as sql_variant), cast(d as sql_variant)) 
	, d = choose(2, cast(c as sql_variant), cast(d as sql_variant)) 
from #t
)
select 
	c
	, d
	, sql_variant_property (c, 'BaseType')
	, sql_variant_property (d, 'BaseType')
from a

drop table #t