SELECT
SEPTEMBER.ID_CASE_WELFARE,
SEPTEMBER.AMT_MTD_ASSIST_EXPND
FROM SEPTEMBER INNER JOIN AUGUST ON (SEPTEMBER.AMT_MTD_ASSIST_EXPND > AUGUST.AMT_MTD_ASSIST_EXPND)
AND (SEPTEMBER.ID_CASE_WELFARE = AUGUST.ID_CASE_WELFARE);

Can someone show me, if it is possible, how to return only cases from this query where the
SEPTEMBER.AMT_MTD_ASSIST_EXPND is two times the AUGUST.AMT_MTD_ASSIST_EXPND.

This query gives me cases where september is greater than august

Thanks

Hows about:
SELECT
SEPTEMBER.ID_CASE_WELFARE,
SEPTEMBER.AMT_MTD_ASSIST_EXPND
FROM SEPTEMBER INNER JOIN AUGUST ON (SEPTEMBER.AMT_MTD_ASSIST_EXPND >= (AUGUST.AMT_MTD_ASSIST_EXPND * 2))
AND (SEPTEMBER.ID_CASE_WELFARE = AUGUST.ID_CASE_WELFARE);