Error while using trigger and sequences

Question

hi friends
i am leraning oracle now. i have confronted a difficulty while working with triggers and sequence . iF anybody knows this problem ,please help me
i created atable with the specifications given below
CREATE TABLE TESTSEQ
idno NUMERIC(10),
data1 VARCHAR2(50)
and i created a sequence named seqcol1
CREATE SEQUENCE seqcol1
MINVALUE 1
MAXVALUE 100
START WITH 1
INCREMENT BY 1
CACHE 20;
I created a trigger also named
CREATE OR REPLACE TRIGGER trigADD2
BEFORE
INSERT ON TESTSEQ
FOR EACH ROW
BEGIN
SELECT seqcol.NEXTVAL INTO idno;
END;
My plan is to add the idno automatically from sequence while inserting a value in data1 column
while doing insert operation ,
INSERT INTO TESTSEQ (data1) VALUES ('ram1')
some error is showing
the error is SCOTT.trigADD2 is invalid and failed re-validation
if anybody can help me please help me
thanks and regards

Answer 1

ops$oskar@test9i$ create table t (n number, s varchar2(1));
Table created.
ops$oskar@test9i$ create sequence s;
Sequence created.
ops$oskar@test9i$ insert into t values (s.nextval,'X');
1 row created.
ops$oskar@test9i$ insert into t values (s.nextval,'Y');
1 row created.
ops$oskar@test9i$ insert into t values (s.nextval,'Z');
1 row created.
ops$oskar@test9i$ select * from t;
         N S
         1 X
         2 Y
         3 ZWhat do you need a trigger for?