declare @col varchar(255), @cmd varchar(max);
DECLARE @Select VARCHAR(3000)
DECLARE @Werteneu VARCHAR(3000)
DECLARE @Tablename  VARCHAR(3000)

SELECT @Tablename = 'AD'
DECLARE getinfo cursor for

SELECT c.name FROM sys.tables t JOIN sys.columns c ON t.Object_ID = c.Object_ID
WHERE t.Name = @Tablename
SELECT @Werteneu = @Tablename
OPEN getinfo
FETCH NEXT FROM getinfo into @col
WHILE @@FETCH_STATUS = 0
BEGIN
    IF EXISTS (SELECT TOP 1 * FROM AD WHERE ' + @col + ' IS NOT NULL) BEGIN
    END
    FETCH NEXT FROM getinfo into @col
END
CLOSE getinfo
DEALLOCATE getinfo
exec ('select ' + @Werteneu + ' from AD')