Oracle SQL: PLS-00049 Bad Bind variable when selecting NEXTVAL from a sequence - oracle

Question

So, I'm trying to use JDBC to access my Oracle DB, and I found out that, for the functions in JDBC to return results correctly, I need to make an iterator for my tables. So, after searching around and figuring out what that means, I came up with the following code snippet to get that done:
--create a sequence for use in the trigger
CREATE SEQUENCE accounts_seq;
--make the trigger on insert or update
CREATE OR REPLACE TRIGGER account_pk_trig
BEFORE INSERT OR UPDATE ON accounts
FOR EACH ROW
BEGIN
IF inserting THEN
SELECT : accounts_seq.NEXTVAL INTO : NEW.accountnumber FROM dual;
ELSE IF updating THEN
SELECT : OLD.accountnumber INTO : NEW.accountnumber FROM dual;
END IF;
END IF;
END;
/
And, not only is Oracle SQL Developer putting the dreaded red underline of doom in the space after the semicolon put after end, but also on the forward slash to end the code block. As far as I've seen, this appears to be correct to the Oracle SQL examples of trigger definitions that I've seen... and I'm not sure if this is due to the Oracle SQL Developer not recognizing NEXTVAL as a keyword... because it isn't highlighted like the others are.
After some fiddling around, I realized that the "ELSE IF" opened a new IF statement that I didn't close. But, still getting Bad Bind variable error.
For those of you who would want to make sure that the "accountnumber" field exists in the table "accounts", here's my definition for the "accounts" table.
CREATE TABLE accounts (
accountnumber NUMBER NOT NULL,
routingnumber NUMBER NOT NULL,
acctype VARCHAR2(20),
balance NUMBER (*,2),
ownerid NUMBER,
CONSTRAINT accountnumber_pk PRIMARY KEY (accountnumber)
);

Answer 1

You have two major errors in your PL/SQL code:
First the select : is wrong. You can't just throw in a colon like that. The NEW and OLD records do need a colon, but without a space. :new, not : new.
To store the result of a query in a variable you need:
select accounts_seq.NEXTVAL
INTO :NEW.accountnumber
FROM dual;
But you don't need a SELECT for that, you can use a simple variable assignment:
:NEW.accountnumber := accounts_seq.NEXTVAL;
You also have two END IFs although you only have a single IF
And as documented in the manual it needs to be ELSIF, not ELSE IF
Putting all that together, your trigger should be:
CREATE OR REPLACE TRIGGER account_pk_trig
BEFORE INSERT OR UPDATE ON accounts
FOR EACH ROW
BEGIN
IF inserting THEN
:NEW.accountnumber := accounts_seq.NEXTVAL;
ELSIF updating THEN
:NEW.accountnumber := :OLD.accountnumber;
END IF;
END;
/
As the trigger is declared as BEFORE INSERT OR UPDATE the ELSIF is actually useless, because it can only be insert or updating nothing else. So instead of ELSIF updating THEN you could simply write ELSE