Non duplicate records with max date query on oracle - sql

Question

Hello i have a problem with a simple query. I need to see the max date of some articles in two direfent sites.
This is my actual query:
SELECT a.aa_codart, MAX(t.tr_fechafac), t.tr_tipo
FROM ARTALM a, traspaso t
WHERE t.tr_codart = a.aa_codart
and t.tr_tipomov > 1
and a.aa_codalm = '1'
and (t.tr_tipo >= 1 and t.tr_tipo <=2)
group by a.aa_codart, t.tr_tipo;
And the result:
01..FRB10X80 30/11/07 2
01..FRB10X80 08/03/01 1
01.32122RS 05/02/16 1
01.32122RS 02/07/10 2
01.33052Z 21/09/15 1
01.60042Z 24/02/16 2
I want, for example in the two first rows, see only one row, like this:
01..FRB10X80 30/11/07 2
01.32122RS 05/02/16 1
01.33052Z 21/09/15 1
01.60042Z 24/02/16 2
Taking the max date
Thanks

Answer 1

This calls for an analytical query. This query shows how the ROW_NUMBER() function will assign the value 1 to the row with the article's most recent date. Give it a try first to help understand the final query, coming up next:
SELECT
a.aa_codart,
t.tr_fechafac,
t.tr_tipo,
ROW_NUMBER() OVER (PARTITION BY a.aa_codart ORDER BY t.tr_fechafac DESC) as rnk
FROM artalm a
INNER JOIN trapaso t ON a.aa_codart = t.tr_codart
WHERE t.tr_tipomov > 1
AND a.aa_codalm = '1'
AND t.tr_tipo BETWEEN 1 AND 2
You can't apply the WHERE clause to the rnk column because the column is calculated after the WHERE clause. You can get around this using a nested query:
SELECT * FROM (
SELECT
a.aa_codart,
t.tr_fechafac,
t.tr_tipo,
ROW_NUMBER() OVER (PARTITION BY a.aa_codart ORDER BY t.tr_fechafac DESC) as rnk
FROM artalm a
INNER JOIN trapaso t ON a.aa_codart = t.tr_codart
WHERE t.tr_tipomov > 1
AND a.aa_codalm = '1'
AND t.tr_tipo BETWEEN 1 AND 2
) WHERE rnk = 1;
I apologize in advance for any column names I may have retyped badly. The Oracle syntax should be fine; the column names maybe not so much :)

Answer 2

I think you may want to look at row_number() (then just pick the ones where it is one) something like this.
WITH t
AS (SELECT 'A' aa_codart,
TO_DATE ('17/05/00', 'dd/mm/yy') mydt,
1 tr_tipo
FROM DUAL
UNION ALL
SELECT 'A', TO_DATE ('12/04/00', 'dd/mm/yy'), 2 FROM DUAL
UNION ALL
SELECT 'B', TO_DATE ('30/06/98', 'dd/mm/yy'), 2 FROM DUAL
UNION ALL
SELECT 'C', TO_DATE ('30/06/98 ', 'dd/mm/yy'), 2 FROM DUAL),
t2
AS (SELECT aa_codart,
mydt,
tr_tipo,
ROW_NUMBER ()
OVER (PARTITION BY aa_codart ORDER BY mydt DESC)
rn
FROM t)
SELECT *
FROM t2
WHERE rn = 1