Oracle中每个记录更新的默认值列

Question

How should we update a column with default value on every update statement in Oracle?

Like last update timestamp should have sysdate for every update statement executed

Answer 1

This is a perfect use for a trigger:

CREATE OR REPLACE TRIGGER SOME_TABLE_BU
  BEFORE UPDATE ON SOME_TABLE
  FOR EACH ROW
BEGIN
  :NEW.LAST_UPDATED_TIMESTAMP := SYSDATE;
END SOME_TABLE_BU;

You can extend this easily to handle inserts by using:

CREATE OR REPLACE TRIGGER SOME_TABLE_BIU
  BEFORE INSERT OR UPDATE ON SOME_TABLE
  FOR EACH ROW
BEGIN
  IF INSERTING THEN
    :NEW.INSERTED_TIMESTAMP := SYSDATE;
  ELSIF UPDATING THEN
    :NEW.LAST_UPDATED_TIMESTAMP := SYSDATE;
  END IF;
END SOME_TABLE_BIU;

Best of luck.