As the others have suggested, in SQL Server you can use a datatype of
BIT[
^]
See also
SQL Data Type Mappings[
^]
Note that the database handlers built into .net should take care of any conversion for you. For example you can do something like this...
SqlCommand cmd = new SqlCommand("insert into Product (ProductName, Active) values(@prod, @active)", con);
cmd.Parameters.AddWithValue("@prod", "A new product");
cmd.Parameters.AddWithValue("@active", true);
int rowsAffected = cmd.ExecuteNonQuery();