Einschränkungen bei der Konstruktion der Geschäftsjahrestabelle

Create Table FinancialYear
(fiscal_year INTEGER NOT NULL PRIMARY KEY,
start_date DATE NOT NULL,
CHECK ((EXTRACT(YEAR FROM start_date)=fiscal_year-1)
AND (EXTRACT (MONTH FROM start_date)=10)
AND (EXTRACT(DAY FROM start_date)=1),
end_date DATE NOT NULL,
CONSTRAINT valid_end_date
CHECK ((EXTRACT (YEAR FROM end_date)=fiscal_year)
AND (EXTRACT (MONTH FROM end_date)=9)
AND (EXTRACT (DAY FROM end_date)=30)))