SQL Query for last year 30 days in Oracle - sql

Question

In Oracle, I would like to get data for:
last 30 days from the current date and
also for the last 30 days from the (current date - 365) which is previous year
I was able to do so successfully for the first item:
WHERE CREATE_TIMESTAMP > SYSDATE - 30
But not sure how to achieve that for the second item. I tried:
WHERE CREATE_TIMESTAMP BETWEEN ((SYSDATE - 395) AND (SYSDATE - 365))
Moreover, my CREATE_TIMESTAMP is a timestamp column.

Answer 1

If you are just trying to get a list of those dates which are within the last 30 days of either this year or the same dates of last year then:
SELECT TRUNC(SYSDATE) - LEVEL + 1
FROM DUAL
CONNECT BY LEVEL <= 30
UNION ALL
SELECT ADD_MONTHS( TRUNC(SYSDATE) - LEVEL + 1, -12 )
FROM DUAL
CONNECT BY LEVEL <= 30
If you are trying to restrict the data from a query to only those dates then:
WHERE ( date_column BETWEEN sysdate - 30
AND sysdate
OR date_column BETWEEN ADD_MONTHS( sysdate, -12 ) - 30
AND ADD_MONTHS( sysdate, -12 )
)
Or if you are particularly worried about the conversion from TIMESTAMP to a DATE in the above filter then you can use the function below:
CREATE OR REPLACE FUNCTION TS_ADD_MONTHS(
datetime TIMESTAMP,
months INT
) RETURN TIMESTAMP DETERMINISTIC
AS
p_date CONSTANT DATE := TRUNC( datetime );
BEGIN
RETURN CAST( ADD_MONTHS( p_date, months ) AS TIMESTAMP )
+ ( datetime - p_date );
END;
/
SHOW ERRORS;
Then in your query can use:
WHERE ( date_column BETWEEN SYSTIMESTAMP - INTERVAL '30' DAY
AND SYSTIMESTAMP
OR date_column BETWEEN TS_ADD_MONTHS( sysdate, -12 ) - INTERVAL '30' DAY
AND TS_ADD_MONTHS( sysdate, -12 )
)