How do I return all data for the previous month in SQL?

Question

How do I return all data for the previous month in SQL. (NOT SQL SERVER). This is the code I have.

SELECT     DOD
FROM       ZZZ_DEPARTURE_DATES
WHERE      DOD = (MONTH, -1, GETDATE());

Answer 1

For Oracle:

SELECT     DOD
FROM       ZZZ_DEPARTURE_DATES
WHERE      DOD >= TRUNC(ADD_MONTHS(SYSDATE,-1),'MON')
AND        DOD < TRUNC(SYSDATE,'MON');

Note: using this syntax is more likely to take advantage of an index on DOD , if one exists.