遗失了故人
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 n
C. The CREATE SEQUENCE command would not execute because the starting value of the sequence and the increment value have
D. All the statements would execute successfully and the ORD_NO column would have the value 20 for the CUST_ID 101 because the
20.
Answer: A
QUESTION 45
Which two statements are true about sequences created in a single instance database? (Choose two.)
A. The numbers generated by a sequence can be used only for one table.
B. DELETE <sequencename> would remove a sequence from the database.
C. CURRVAL is used to refer to the last sequence number that has been generated.
D. When the MAXVALUE limit for a sequence is reached, you can increase the MAXVALUE limit by using the ALTER SEQUENCE staE. When a database instance shuts down abnormally, the sequence numbers that have been cached but not used would be available
database instance is restarted.
Answer: CD
QUESTION 46
Which statements are correct regarding indexes? (Choose all that apply.)
A. When a table is dropped, the corresponding indexes are automatically dropped.
B. A FOREIGN KEY constraint on a column in a table automatically creates a nonunique index.
C. A nondeferrable PRIMARY KEY or UNIQUE KEY constraint in a table automatically creates a unique index.
D. For each data manipulation language (DML) operation performed, the corresponding indexes are automatically updated.
