How select second max value from a subquery - sql

Question

I need to select a max date (DATA_RIF_PATR_KU) for the key PROT, CODICE_COM, but there are also 9999-12-31 values. So when there are others date than 9999-12-31 I need to select the "real max date" else 9999-12-31.
For example:
For the combination:
PROT = '202000060300' AND
CODICE_COM='Z01'
I have 2 dates of DATA_RIF_PATR_KU: 03-11-20, 9999-12-31. I need to select the first one.
I wrote this code:
'''
SELECT
A.GRADO,
A.COMM,
A.PROT,
MAX(A.FLAG_VAL_IND) AS FLAG_VAL_IND,
SUM(A.CONT_VERS) AS CONT_VERS,
SUM(A.IMP_PREN) AS IMP_PREN,
SUM(A.CONT_DIFF) AS CONT_DIFF,
MIN(A.DATA_VER) AS DATA_VER,
MAX(A.PREN_DEB) AS PREN_DEB,
MAX(A.PREN_DEB_VER) AS PREN_DEB_VER,
MAX(A.GRAT_PATR_KU) AS GRAT_PATR_KU,
MAX(CASE WHEN (A.MAX_DATA_RIF_PATR_NON_9999)='SI' THEN A.DATA_RIF_PATR_KU
WHEN (A.MAX_DATA_RIF_PATR_NON_9999_2)='SI2' THEN A.DATA_RIF_PATR_KU END) AS DATA_RIF_PATR_KU,
SUM(A.MAGG_PEC) AS MAGG_PEC,
MAX(A.ASS_PEC) AS ASS_PEC,
MAX(A.ASS_CF) AS ASS_CF,
MAX(A.ASS_VAL) AS ASS_VAL,
MAX(A.FLAG_LAV) AS FLAG_LAV,
SUM(A.CONT_DIC) AS CONT_DIC,
SUM(A.CONT_TOT) AS CONT_TOT,
SUM(A.CONT_DIFF_VERIF) AS CONT_DIFF_VERIF,
MAX(A.DATA_AGG) AS DATA_ULTIMA_VALIDAZIONE,
MAX(CASE WHEN (A.DATA_INV)<'9999-12-31'
THEN '1'
ELSE '0' END) AS PRESENZA_INVITO_PAG,
MAX(CASE WHEN (A.DATA_VERS_INV)<'9999-12-31'
THEN '1'
ELSE '0' END) AS PRESENZA_VERS_INVITO
FROM
(
SELECT
distinct BILS05_GRADO AS GRADO,
BILS05_CODICE_COM AS COMM,
BILS05_PROT AS PROT,
CASE WHEN BILS05_FLAG_VAL_IND IN ('0','9')
THEN 'D'
ELSE 'I' END AS FLAG_VAL_IND,
bils05_tipo_doc, bils05_prog_alleg, bils05_pren_deb as pren_deb,
BILS05_PREN_DEB_VERIF AS PREN_DEB_VER,
CASE WHEN BILS05_PREN_DEB='1' AND BILS05_PREN_DEB_VERIF='1'
THEN 0
ELSE BILS05_CONT_VERS_VERIF END AS CONT_VERS,
CASE WHEN BILS05_PREN_DEB='1' AND BILS05_PREN_DEB_VERIF='1'
THEN BILS05_CONT_VERS_VERIF
ELSE 0 END AS IMP_PREN,
BILS05_CONT_DIFF AS CONT_DIFF,
BILS05_DATA_ACQ_KU AS DATA_VER,
BILS05_MAGG_PEC AS MAGG_PEC,
BILS05_ASS_PEC AS ASS_PEC,BILS05_ASS_CF AS ASS_CF,BILS05_ASS_VAL AS ASS_VAL,
BILS05_FLAG_LAV AS FLAG_LAV,
BILS05_CONT_VERS AS CONT_DIC,
BILS05_CONT_TOT AS CONT_TOT,
BILS05_CONT_DIFF_VERIF AS CONT_DIFF_VERIF,
BILS05_DATA_AGG_KU AS DATA_AGG,
BILS05_DATA_INV_PAG AS DATA_INV,
BILS05_DATA_VERS_INV AS DATA_VERS_INV,
BILS05_GRAT_PATR as GRAT_PATR_KU,
BILS05_DATA_RIF_PATR AS DATA_RIF_PATR_KU,
ROW_NUMBER() OVER(PARTITION BY BILS05_PROT, BILS05_CODICE_COM ORDER BY BILS05_DATA_RIF_PATR) AS RN,
LEAD(DATA_RIF_PATR_KU) OVER(PARTITION BY BILS05_PROT, BILS05_CODICE_COM ORDER BY DATA_RIF_PATR_KU) AS FOLLOW_DATA,
LAG(DATA_RIF_PATR_KU) OVER(PARTITION BY BILS05_PROT, BILS05_CODICE_COM ORDER BY DATA_RIF_PATR_KU) AS PREV_DATA,
CASE WHEN (DATA_RIF_PATR_KU < FOLLOW_DATA AND DATA_RIF_PATR_KU NOT = '9999-12-31' AND FOLLOW_DATA='9999-12-31' )THEN 'SI'
ELSE 'NO' END AS MAX_DATA_RIF_PATR_NON_9999,
CASE WHEN (DATA_RIF_PATR_KU NOT = '9999-12-31' AND FOLLOW_DATA IS NULL) OR (DATA_RIF_PATR_KU = '9999-12-31' AND FOLLOW_DATA IS NULL)
THEN 'SI2' ELSE 'NO' END AS MAX_DATA_RIF_PATR_NON_9999_2
FROM ZUCOW.BILS05
WHERE
BILS05_FLAG_LAV='2'
) A
WHERE
A.PROT='202000060300' AND
A.COMM='Z01'
GROUP BY A.GRADO, A.COMM, A.PROT;
'''
but it doesn't work properly. It select 9999-12-31 instead of 03-11-20 in the above example

Answer 1

Your example is rather long and complex, but the general idea would be
(assuming DATA_RIF_PATR_KU is a date field):
select
max(case when DATA_RIF_PATR_KU='9999-12-31' then null else DATA_RIF_PATR_KU end),
PROT, CODICE_COM
FROM FROM ZUCOW.BILS05
GROUP BY 2,3

Answer 2

yes that's the general idea.. Anyway at the end, I solved it in another way:
MAX(CASE WHEN TO_CHAR(A.DATA_RIF_PATR_KU, 'YYYY-MM-DD' ) LIKE ('9999-12-31')THEN '0000-12-31' ELSE TO_CHAR(A.DATA_RIF_PATR_KU, 'YYYY-MM-DD') END) AS DATA_RIF_PATR_KU_STR
So, I converted the 9999-12-31 values in 0000-12-31 (I had to to transform the date value in string), so then I could do the max and then I converted the values back in the ETL software.
Thank You all for helping