SQL find non-null columns

select max(field1),max(field2),max(field3),...
   from series where t_stamp between x and y

SELECT
     CASE WHEN EXISTS (SELECT * FROM Series WHERE t_stamp BETWEEN @x AND @y AND field1 IS NOT NULL) THEN 1 ELSE 0 END AS field1,
     CASE WHEN EXISTS (SELECT * FROM Series WHERE t_stamp BETWEEN @x AND @y AND field2 IS NOT NULL) THEN 1 ELSE 0 END AS field2,
...

create table series (fieldno integer, t_stamp date);

select distinct fieldno from series where t_stamp between x and y;

select 'field1' as fieldname from series
   where field1 is not null and t_stamp between x and y
UNION
select 'field2' from series where field2 is not null
... etc

select count(field1),count(field2),count(field3),...
   from series where t_stamp between x and y

SELECT CASE WHEN field1 IS NOT NULL THEN '' ELSE 'contains null' END AS field1_stat,
       CASE WHEN field2 IS NOT NULL THEN '' ELSE 'contains null' END AS field2_stat,
... for every field to be checked
FROM   series
WHERE  foo IN bar
GROUP BY CASE WHEN field1 IS NOT NULL THEN '' ELSE 'contains null' END,
         CASE WHEN field2 IS NOT NULL THEN '' ELSE 'contains null' END
... etc