View the Exhibit and examine the structure of the ORD table.
Evaluate the following SQL statements that are executed in a user session in the specified order:
CREATE SEQUENCE ord_seq;
SELECT ord_seq.nextval
FROM dual;
INSERT INTO ord
VALUES (ord_seq.CURRVAL, ’25-jan-2007′,101);
UPDATE ord
SET ord_no= ord_seq.NEXTVAL
WHERE cust_id =101;
What would be the outcome of the above statements?
A.
All the statements would execute successfully and the ORD_NO column would contain the value 2 for the CUST_ID 101.
B.
The CREATE SEQUENCE command would not execute because the minimum value and maximum value for the sequence have not been specified.
C.
The CREATE SEQUENCE command would not execute because the starting value of the sequence and the increment value have not been specified.
D.
All the statements would execute successfully and the ORD_NO column would have the value 20 for the CUST_ID 101 because the default CACHE value is 20.
Answer is A
CREATE SEQUENCE ord_seq13;
SELECT ord_seq13.nextval FROM dual;
SELECT ord_seq13.currval FROM dual;
drop SEQUENCE ord_seq13;
1.To create a sequence that increments without bound, for ascending sequences, omit the MAXVALUE parameter or specify NOMAXVALUE. For descending sequences, omit the MINVALUE parameter or specify the NOMINVALUE.
2.To create a sequence that stops at a predefined limit, for an ascending sequence, specify a value for the MAXVALUE parameter. For a descending sequence, specify a value for the MINVALUE parameter. Also specify NOCYCLE. Any attempt to generate a sequence number once the sequence has reached its limit results in an error.
3.To create a sequence that restarts after reaching a predefined limit, specify values for both the MAXVALUE and MINVALUE parameters. Also specify CYCLE. If you do not specify MINVALUE, then it defaults to NOMINVALUE, which is the value 1.