How can I use SUM for bit columns?

Question

How can use the function SUM() for bit columns in T-SQL?

When I try do it as below:

SELECT SUM(bitColumn) FROM MyTable;

I get the e

Answer 1

Somewhat cryptically:

declare @Foo as Bit = 1;
-- @Foo is a Bit.
select SQL_Variant_Property( @Foo, 'BaseType' );
-- But adding zero results in an expression with data type Int.
select SQL_Variant_Property( @Foo + 0, 'BaseType' );
select Sum( @Foo + 0 );

declare @Samples as Table ( Foo Bit );
insert into @Samples ( Foo ) values ( 0 ), ( 1 ), ( 0 ), ( 0 ), ( 1 ), ( 1 ), ( 1 ), ( 1 );
select Sum( Foo + 0 ) from @Samples;

This certainly doesn't improve readability or maintainability, but it is compact.