Trigger SQL statement - sql

Question

Hi so I have am writing a statement to create a trigger in Oracle that would append the text to the description of every new game inserted into the database.
I want the format to be like
Format: (rating). (Name) is (Genre)
Example: M18. Dragon Ball, Genre is Fighting/Adventure.
GenreID and subGenre in Game Table is foreign key to Genre Table.
GameID Sequence
CREATE SEQUENCE "GAME_ID_SEQ" MINVALUE 100 MAXVALUE 999999999
INCREMENT BY 5 START WITH 100;
GameID Trigger
CREATE OR REPLACE TRIGGER "tr_gameID"
BEFORE INSERT ON "GAME"
FOR EACH ROW
BEGIN
SELECT "GAME_ID_SEQ".NEXTVAL INTO :NEW.gameID FROM DUAL;
END;
/
Game Description Trigger
CREATE OR REPLACE TRIGGER "GAME_DES"
BEFORE INSERT OF GAME
FOR EACH ROW
DECLARE
gen VARCHAR2(8);
subGen VARCHAR2(8);
BEGIN
SELECT name INTO gen FROM GENRE WHERE GenreID = :NEW.GenreID;
SELECT name INTO subGen FROM GENRE WHERE subGenreID = :NEW.GenreID;
SELECT CONCAT(rating,".", title ,"Genre is", gen, "/", subGen) INTO :NEW.description FROM DUAL;
END;
/
I'm not sure where I'm doing wrong. But I keep getting "Warning: Trigger created with compilation errors."

Answer 1

What did you do wrong? Several things.
TR_GAMEID is OK (although, could be rewritten as)
SQL> create or replace trigger tr_gameid
2 before insert on game
3 for each row
4 begin
5 :new.gameid := game_id_seq.nextval;
6 end;
7 /
Trigger created.
GAME_DES isn't OK, suffers from various errors.
it isn't before insert OF but ON
the 2nd select refrences subgenreid column from the genre table, but - according to what you posted - such a column doesn't exist in the table (but exists in game)
concat allows only 2 parameters. You'd rather switch to double pipe || concatenation operator.
also, you're concatenating some rating and title things which are unknown. What are they?
The following trigger compiles but is probably wrong as the 2nd select looks suspicious.
SQL> create or replace trigger game_Des
2 before insert on game
3 for each row
4 declare
5 gen varchar2(8);
6 subgen varchar2(8);
7 begin
8 select name into gen from genre where genreid = :new.genreid;
9 select name into subgen from genre where genreid = :new.genreid;
10 :new.description := 'Genre is ' || gen ||'/'|| subgen;
11 end;
12 /
Trigger created.
SQL>
Also, a piece of advice: when Oracle says you got errors, ask it which ones they were. How? Like this (in SQL*Plus) (this is your code):
SQL> CREATE OR REPLACE TRIGGER "GAME_DES"
2 BEFORE INSERT ON GAME --> I fixed this
3 FOR EACH ROW
4 DECLARE
5 gen VARCHAR2(8);
6 subGen VARCHAR2(8);
7 BEGIN
8 SELECT name INTO gen FROM GENRE WHERE GenreID = :NEW.GenreID;
9 SELECT name INTO subGen FROM GENRE WHERE subGenreID = :NEW.GenreID;
10 SELECT CONCAT(rating,".", title ,"Genre is", gen, "/", subGen) INTO :NEW.description FROM DUAL;
11 END;
12 /
Warning: Trigger created with compilation errors.
SQL> show err
Errors for TRIGGER "GAME_DES":
LINE/COL ERROR
-------- -----------------------------------------------------------------
7/3 PL/SQL: SQL Statement ignored
7/10 PL/SQL: ORA-00909: invalid number of arguments
SQL>
Alternatively, query USER_ERRORS:
SQL> select text, line, position
2 from user_errors
3 where name = 'GAME_DES';
TEXT LINE POSITION
-------------------------------------------------- ---------- ----------
PL/SQL: ORA-00909: invalid number of arguments 7 10
PL/SQL: SQL Statement ignored 7 3
SQL>