单项选择题 A number of applications issue the following SQL statement:SELECT d.deptno, e.empno, e.salary FROM department d INNER JOIN employee e ON d.deptno = e.deptnoA database administrator wishes to store this query within the database. Which of the following database objects can be used to accomplish this?（）

单项选择题 The following statements: CREATE TABLE t1 (col1 INT NOT NULL, PRIMARY KEY(col1)); CREATE TABLE t2 (col1 INT NOT NULL, col2 CHAR(1) NOT NULL, PRIMARY KEY (col1, col2), FOREIGN KEY (col1) REFERENCES t1 (col1) ON DELETE CASCADE ON UPDATE RESTRICT); CREATE TABLE t3 (col1 INT NOT NULL, col2 INT NOT NULL, PRIMARY KEY (col1, col2),FOREIGN KEY (col1) REFERENCES t1 (col1) ON DELETE NO ACTION ON UPDATE RESTRICT);INSERT INTO t1 VALUES (1), (2); INSERT INTO t2 VALUES (1, a), (1, b), (2,c); INSERT INTO t3 VALUES (1, 100), (2, 200), (2,300); How many rows will be deleted by the following DELETE statement? DELETE FROM t1 WHERE col1= 1;（）

单项选择题 Within the application MY_APP the following PREVIOUS VALUE expression references the sequence MY_SEQ: PREVIOUS VALUE FOR my_seq After which of the following events will the most recently generated value of MY_SEQ persist so that it can be returned to the active MY_APP application?（）