Let's assume I extract some set of data.
i.e.
SELECT A, date
FROM table
I want just the record with the max date (for each value of A). I could write
SELECT A, col_date
FROM TABLENAME t_ext
WHERE col_date = (SELECT MAX (col_date)
FROM TABLENAME t_in
WHERE t_in.A = t_ext.A)
But my query is really long... is there a more compact way using ANALYTIC FUNCTION to do the same?
The analytic function approach would look something like
SELECT a, some_date_column
FROM (SELECT a,
some_date_column,
rank() over (partition by a order by some_date_column desc) rnk
FROM tablename)
WHERE rnk = 1
Note that depending on how you want to handle ties (or whether ties are possible in your data model), you may want to use either the ROW_NUMBER
or the DENSE_RANK
analytic function rather than RANK
.