更改错误日期的 SQL 触发器

Question

how can I make an SQL trigger in Oracle, which will check day and month of date inserted and if it's not Jan 1st, the trigger updates it?

Example:

CREATE TABLE Contract (
Ends_on DATE NOT NULL 
);

INSERT INTO Contract (Ends_on)
VALUES (TO_DATE('2017-1-30','yyyy-mm-dd'));

in this case, the date should automatically change to '2017-1-1'

Thanks in advance

Answer 1

The trigger would look like this, making use of the TRUNC function with second argument 'YEAR' :

CREATE OR REPLACE TRIGGER trg_ins_contract
    BEFORE INSERT ON Contract 
    FOR EACH ROW
BEGIN
    :new.Ends_on := TRUNC(:new.Ends_on, 'YEAR');
END;
/