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?（）

单项选择题 Given the following ALTER SEQUENCE statement: ALTER SEQUENCE myseq RESTART WITH 0 INCREMENT BY 1 NO MAXVALUE CACHE 5 ORDER Assuming that the sequence had reached a value of 100 prior to the RESTART, which of the following is true?（）