JDBC导航结果集示例

以下是利用在结果集教程中描述一些导航方法的例子。

基于对环境和数据库安装在前面的章节中做此示例代码已被写入。

复制下面的例子JDBCExample.java,编译并运行,如下所示:

//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: Execute a query to create statment with // required arguments for RS example. System.out.println("Creating statement..."); stmt = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); String sql; sql = "SELECT id, first, last, age FROM Employees"; ResultSet rs = stmt.executeQuery(sql); // Move cursor to the last row. System.out.println("Moving cursor to the last..."); rs.last(); //STEP 5: Extract data from result set System.out.println("Displaying record..."); //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); // Move cursor to the first row. System.out.println("Moving cursor to the first row..."); rs.first(); //STEP 6: Extract data from result set System.out.println("Displaying record..."); //Retrieve by column name id = rs.getInt("id"); age = rs.getInt("age"); first = rs.getString("first"); 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); // Move cursor to the first row. System.out.println("Moving cursor to the next row..."); rs.next(); //STEP 7: Extract data from result set System.out.println("Displaying record..."); id = rs.getInt("id"); age = rs.getInt("age"); first = rs.getString("first"); 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); //STEP 8: Clean-up environment rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ //Handle errors for JDBC se.printStackTrace(); }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}//end JDBCExample

现在让我们来编译上面的例子如下: