DECODE function to validate date value and sort the records

Question

Hi Friends,
I am looking for some query which can give me the required output,
I need to do this using SQL query only and I have tried using the MIN() and MAX() functions it was working fine with limited data, now after inserting the last record(in the below table) which has date for start_range and end_range in(mm/dd/yyyy hh24:mi:ss) format.
Because the data type is VARCHAR2 if I am using the MIN() function it is sorting as a string value, hence the min date is incorrect. I tried using validating the value to date or non date and tried to using MIN() and MAX() functions using the DECODE function, I am getting this error "ORA-01840: input value not long enough for date format".
select table_name,
DECODE(substr(START_RANGE,3,1)||substr(START_RANGE,6,1)||substr(START_RANGE,11,1)||substr(START_RANGE,14,1)||substr(START_RANGE,17,1),'// ::',
to_char(min(to_date(start_range,'mm/dd/yyyy hh24:mi:ss')),'MM/DD/YYYY HH24:MI:SS'),min(start_range)) MIN_RUNS_START_RANGE,
DECODE(substr(END_RANGE,3,1)||substr(A.END_RANGE,6,1)||substr(END_RANGE,11,1)||substr(END_RANGE,14,1)||substr(END_RANGE,17,1),'// ::',
to_char(max(to_date(END_RANGE,'mm/dd/yyyy hh24:mi:ss')),'MM/DD/YYYY HH24:MI:SS'),max(END_RANGE)) MAX_RUNS_END_RANGE
from MY_TABLE
GROUP BY table_name,
(substr(START_RANGE,3,1)||substr(START_RANGE,6,1)||substr(START_RANGE,11,1)||substr(START_RANGE,14,1)||substr(START_RANGE,17,1)),
(substr(END_RANGE,3,1)||substr(END_RANGE,6,1)||substr(END_RANGE,11,1)||substr(END_RANGE,14,1)||substr(END_RANGE,17,1))
Can sombody please advise what is the best way I can query this data with the required output.
The following are the source table and records and the out put records using the sql query.
MY_TABLE
TABLE_NAME(VARCHAR2),START_RANGE(VARCHAR2),END_RANGE(VARCHAR2)
TABLE1,1000,10000
TABLE2,ABCD,EEEE
TABLE3,01/12/2010 00:00:00,12/31/2010 23:59:59
TABLE1,10001,20000
TABLE2,EEEF,GGGG
TABLE3,01/01/2011 00:00:00,01/31/2011 23:59:59
OUTPUT :
TABLE_NAME,MIN(START_RANGE),MAX(END_RANGE)
TABLE1,1000,20000
TABLE2,ABCD,GGGG
TABLE3,01/12/2010 00:00:00,01/31/2011 23:59:59
Thanks
Kalycs

Answer 1

i also think this is a very bad table design ...
but if you are not able to change it, you could split the select (date and non-date data) and combine the result with UNION like this:
with t as
SELECT 'TABLE1' table_name,'1000' start_range,'10000' end_range FROM dual UNION
SELECT 'TABLE2','ABCD','EEEE' FROM dual UNION
SELECT 'TABLE3','01/12/2010 00:00:00','12/31/2010 23:59:59' FROM dual UNION
SELECT 'TABLE1','10001','20000' FROM dual UNION
SELECT 'TABLE2','EEEF','GGGG' FROM dual UNION
SELECT 'TABLE3','01/01/2011 00:00:00','01/31/2011 23:59:59' FROM dual
SELECT table_name,
       TO_CHAR(MIN(TO_DATE(start_range, 'MM/DD/YYYY HH24:MI:SS')), 'MM/DD/YYYY HH24:MI:SS'),
       TO_CHAR(MAX(TO_DATE(end_range, 'MM/DD/YYYY HH24:MI:SS')), 'MM/DD/YYYY HH24:MI:SS')
FROM t
WHERE start_range LIKE '%/%/%:%:%'
GROUP BY table_name
UNION
SELECT table_name,
       MIN(start_range),
       MAX(end_range)
FROM t
WHERE start_range NOT LIKE '%/%/%:%:%'
GROUP BY
    table_name;
TABLE_ MIN_VALUE           MAX_VALUE
TABLE1 1000                20000
TABLE2 ABCD                GGGG
TABLE3 01/12/2010 00:00:00 01/31/2011 23:59:59