Question

Some data would be organized thusly:

ID DATE COUNT1 COUNT2 
A  20120101 1    2
A  20120201 2    2
B  20120101 3    0
C  20111201 1    0
C  20120301 2    2 

Another table has ID NAME

               A MYNAME
              .... etc

i want to return a table of

ID NAME COUNT COUNT2

for the most recent available piece of data, i.e. the january count for A is not included

i know I need to use HAVING, INNER JOIN, and GROUP BY but every iteration I can come up with has an error.

Answer 1

If you only want rows with the date equal to the global maximum date, just use a subquery:

select ID,DATE,COUNT1,COUNT2
from table
where DATE=(select max(DATE) from table);

If you want the maximum date per ID, then you can use a self join:

select ID,MAX_DATE,COUNT1,COUNT2
from(
    select ID,max(DATE) as MAX_DATE
    from table
    group by ID
)a
join(
    select ID,DATE,COUNT1,COUNT2
    from table
)b
on (a.ID=b.ID and a.MAX_DATE=b.DATE);