Creating Oracle Sequence Trigger

Question

I'm trying create seuqunce trigger but error occurs when I executing the trigger create sql in SQL Developer. I don't understand, actually everything looks fine. I share the details below, please help me, thanks.

My trigger sql:

CREATE OR REPLACE TRIGGER "TRIGGER1" BEFORE INSERT ON ACCOUNTS
FOR EACH ROW
 WHEN (new."ID" IS NULL) 
BEGIN
  SELECT ACCOUNTS_SEQ.NEXTVAL 
  INTO :new."ID" 
  FROM dual;
END;
/

And error description:

Error starting at line : 5 in command -
CREATE OR REPLACE TRIGGER "TRIGGER1" BEFORE INSERT ON ACCOUNTS
FOR EACH ROW
 WHEN (new."ID" IS NULL) 
BEGIN
  SELECT ACCOUNTS_SEQ.NEXTVAL 
  INTO :new."ID" 
  FROM dual
Error report -
SQL Command: trıgger "TRIGGER1"
Failed: Warning: completed with warning

Error starting at line : 12 in command -
END
Error report -
Unknown Command

Answer 1

Try this:

CREATE OR REPLACE TRIGGER TRIGGER1
BEFORE INSERT ON ACCOUNTS
FOR EACH ROW
  WHEN (new.ID IS NULL)
BEGIN
  :new.ID := ACCOUNTS_SEQ.NEXTVAL;
END;
/

Your sequence should look like this:

CREATE SEQUENCE ACCOUNTS_SEQ 
  START WITH 1 
  INCREMENT BY 1;

Answer 2

CREATE OR REPLACE TRIGGER TRIGGER1
BEFORE INSERT ON ACCOUNTS
FOR EACH ROW
BEGIN
IF :new.ID IS NULL THEN 
SELECT ACCOUNTS_SEQ.NEXTVAL 
INTO :new.ID
FROM dual;
END IF;
END;