Given the code fragment:
What is the result of the employees table has no records before the code executed?
A.
1 Sam
B.
4 Jack
C.
3 John
4 Jack
D.
1 Sam
3 John
4 Jack
Explanation:
AutoCommit is set to false. The two following statements will be within the same transaction.
stmt.executeUpdate(“insert into employees values(1,’Sam’)”);
stmt.executeUpdate(“insert into employees values(2,’Jane’)”);
These two statements are rolled-back through (the savepoint is ignored! the savepoint must be
specified (e.g.
conn.rollback(save1); ) in the rollback if you want to rollback to the savepoint):
conn.rollback() ;
The next two insert statements are executed fine. Their result will be in the output.
Answewr is D
Sorry Answer is not D, the correct answer is C because the rollback undo all the transactions, even if there is a savepoint.
public static void main(String[] args) {
String url = “jdbc:mysql://localhost:3306/employeedb?zeroDateTimeBehavior=convertToNull”;
String username = “userName”;
String password = “password”;
String query = “SELECT * FROM manager”;
try (Connection conn =
DriverManager.getConnection(url, username, password);
Statement stmt = conn.createStatement();) {
try {
conn.setAutoCommit(false);
stmt.executeUpdate(“INSERT INTO manager (first_name) VALUES(‘Sam’);”);
Savepoint save1 = conn.setSavepoint(“point1”);
stmt.executeUpdate(“INSERT INTO manager (first_name) VALUES(‘Jane’);”);
conn.rollback();
//conn.rollback(save1);
stmt.executeUpdate(“INSERT INTO manager (first_name) VALUES(‘Jonh’);”);
conn.setAutoCommit(true);
stmt.executeUpdate(“INSERT INTO manager (first_name) VALUES(‘Jack’);”);
ResultSet rs = stmt.executeQuery(“select * from manager”);
while (rs.next()) {
System.out.println(rs.getString(1) + ” ” + rs.getString(2));
}
} catch (Exception e) {
System.out.print(e.getMessage());
}
} catch (SQLException e) {
System.out.println(“SQL Exception: ” + e);
} // end of try-with-resources
}
delimiter $$
CREATE TABLE `manager` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`first_name` varchar(45) DEFAULT NULL,
`last_name` varchar(45) DEFAULT NULL,
`birth_date` date DEFAULT NULL,
`salary` double DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=16 DEFAULT CHARSET=utf8$$
C
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