Question

I have a table and I would like to get a row containing all the latest non-null attributes for each column (without combining separate queries for each column, which doesn’t seem elegant to me).

Example:

A     B     C     Time
1     a     7     0
NULL  NULL  3     1
3     NULL  4     2
NULL  NULL  6     3

Result I seek:

A     B     C
3     a     6

As I said, I know how to select what I want for each column separately, but I was wondering if there’s a better way to do it. No need to tax the poor database if it isn’t needed.

Answer 1

Probably a better way than this, but it’s Monday and I’m not quite conscious yet:

select @a:=null, @b:=null, @c:=null;
select A,B,C from (
    select @a:=coalesce(A,@a) as A, @b:=coalesce(B,@b) as B, @c:=coalesce(C,@) as C time
    from yourtable
    order by time asc
) as y order by time desc limit 1;

Basically, iterate over each row in the database and build up the “latest” value as you go, then reverse the result set and select only the one with the highest time value