在Java的JDBC使用中设置事务回滚的保存点的方法

try{  //Assume a valid connection object conn  conn.setAutoCommit(false);  Statement stmt = conn.createStatement();    //set a Savepoint  Savepoint savepoint1 = conn.setSavepoint("Savepoint1");  String SQL = "INSERT INTO Employees " +        "VALUES (106, 20, 'Rita', 'Tez')";  stmt.executeUpdate(SQL);   //Submit a malformed SQL statement that breaks  String SQL = "INSERTED IN Employees " +        "VALUES (107, 22, 'Sita', 'Tez')";  stmt.executeUpdate(SQL);  // If there is no error, commit the changes.  conn.commit();}catch(SQLException se){  // If there is any error.  conn.rollback(savepoint1);}

//STEP 1. Import required packagesimport java.sql.*;public class JDBCExample {  // JDBC driver name and database URL  static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";   static final String DB_URL = "jdbc:mysql://localhost/EMP";  // Database credentials  static final String USER = "username";  static final String PASS = "password";  public static void main(String[] args) {  Connection conn = null;  Statement stmt = null;  try{   //STEP 2: Register JDBC driver   Class.forName("com.mysql.jdbc.Driver");   //STEP 3: Open a connection   System.out.println("Connecting to database...");   conn = DriverManager.getConnection(DB_URL,USER,PASS);   //STEP 4: Set auto commit as false.   conn.setAutoCommit(false);   //STEP 5: Execute a query to delete statment with   // required arguments for RS example.   System.out.println("Creating statement...");   stmt = conn.createStatement();  //STEP 6: Now list all the available records.   String sql = "SELECT id, first, last, age FROM Employees";   ResultSet rs = stmt.executeQuery(sql);   System.out.println("List result set for reference....");   printRs(rs);   // STEP 7: delete rows having ID grater than 104   // But save point before doing so.   Savepoint savepoint1 = conn.setSavepoint("ROWS_DELETED_1");   System.out.println("Deleting row....");   String SQL = "DELETE FROM Employees " +          "WHERE ID = 110";   stmt.executeUpdate(SQL);    // oops... we deleted too wrong employees!   //STEP 8: Rollback the changes afetr save point 2.   conn.rollback(savepoint1);  // STEP 9: delete rows having ID grater than 104   // But save point before doing so.   Savepoint savepoint2 = conn.setSavepoint("ROWS_DELETED_2");   System.out.println("Deleting row....");   SQL = "DELETE FROM Employees " +          "WHERE ID = 95";   stmt.executeUpdate(SQL);   //STEP 10: Now list all the available records.   sql = "SELECT id, first, last, age FROM Employees";   rs = stmt.executeQuery(sql);   System.out.println("List result set for reference....");   printRs(rs);   //STEP 10: Clean-up environment   rs.close();   stmt.close();   conn.close();  }catch(SQLException se){   //Handle errors for JDBC   se.printStackTrace();   // If there is an error then rollback the changes.   System.out.println("Rolling back data here....");  try{  if(conn!=null)      conn.rollback();   }catch(SQLException se2){     se2.printStackTrace();   }//end try  }catch(Exception e){   //Handle errors for Class.forName   e.printStackTrace();  }finally{   //finally block used to close resources   try{     if(stmt!=null)      stmt.close();   }catch(SQLException se2){   }// nothing we can do   try{     if(conn!=null)      conn.close();   }catch(SQLException se){     se.printStackTrace();   }//end finally try  }//end try  System.out.println("Goodbye!");}//end main  public static void printRs(ResultSet rs) throws SQLException{   //Ensure we start with first row   rs.beforeFirst();   while(rs.next()){     //Retrieve by column name     int id = rs.getInt("id");     int age = rs.getInt("age");     String first = rs.getString("first");     String last = rs.getString("last");     //Display values     System.out.print("ID: " + id);     System.out.print(", Age: " + age);     System.out.print(", First: " + first);     System.out.println(", Last: " + last);   }   System.out.println();  }//end printRs()}//end JDBCExample

C:>javac JDBCExample.java

C:>java JDBCExample

Connecting to database...Creating statement...List result set for reference....ID: 95, Age: 20, First: Sima, Last: ChugID: 100, Age: 18, First: Zara, Last: AliID: 101, Age: 25, First: Mahnaz, Last: FatmaID: 102, Age: 30, First: Zaid, Last: KhanID: 103, Age: 30, First: Sumit, Last: MittalID: 110, Age: 20, First: Sima, Last: ChugDeleting row....Deleting row....List result set for reference....ID: 100, Age: 18, First: Zara, Last: AliID: 101, Age: 25, First: Mahnaz, Last: FatmaID: 102, Age: 30, First: Zaid, Last: KhanID: 103, Age: 30, First: Sumit, Last: MittalID: 110, Age: 20, First: Sima, Last: ChugGoodbye!