oracle trigger on update and on insert - mysql

Question

I have a table defined in MySQL as following. Now I want to create this table in oracle.
But how can I convert on update trigger in to oracle?
create table test(
userid INTEGER(10) NOT NULL AUTO_INCREMENT,
CONSTRAINT PRIMARY KEY (userid),
fullname VARCHAR(200) NOT NULL,
email VARCHAR(50) NOT NULL,
createdat DATETIME NOT NULL DEFAULT NOW(),
updatedat DATETIME ON UPDATE NOW()
);

Answer 1

For a example, so:
CREATE TABLE test
(
userid INTEGER PRIMARY KEY
, fullname VARCHAR2(200) NOT NULL
, email VARCHAR2(50) NOT NULL
, createdat DATE DEFAULT CURRENT_DATE NOT NULL
, updatedat DATE
);
CREATE SEQUENCE test_seq START WITH 1 INCREMENT BY 1;
CREATE OR REPLACE TRIGGER test_insert
BEFORE INSERT
ON test
FOR EACH ROW
BEGIN
SELECT test_seq.NEXTVAL
INTO :new.userid
FROM DUAL;
END;
CREATE OR REPLACE TRIGGER test_update
BEFORE UPDATE
ON test
FOR EACH ROW
BEGIN
SELECT CURRENT_DATE
INTO :new.updatedat
FROM DUAL;
END;
Triggers may BEFORE UPDATE, AFTER UPDATE, and INSTEAD. Choose that you want. For more information read docs http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_7004.htm

Answer 2

Since Oracle 12c, you can avoid using SEQUENCE in using IDENTITY as done in standard SQL.
The solution to your problem is following
CREATE TABLE test
( userid INTEGER PRIMARY KEY GENERATED ALWAYS AS IDENTITY
, fullname VARCHAR2(200) NOT NULL
, email VARCHAR2(50) NOT NULL
, createdat DATE DEFAULT CURRENT_DATE NOT NULL
, updatedat DATE
);
CREATE OR REPLACE TRIGGER test_update
BEFORE UPDATE
ON test
FOR EACH ROW
BEGIN
SELECT CURRENT_DATE
INTO :new.updatedat
FROM DUAL;
END;