essentialjdbc.java

此程序都是企业级 的数据库开发程序 全面揭示了JAVA对数据库的操作

import java.sql.*;

public class EssentialJDBC {

  public static void main(String[] args) {
    EssentialJDBC SQLExample = 
      new EssentialJDBC();   // Create application object

    SQLExample.getResultsByColumnName();
    SQLExample.getResultsByColumnPosition();
    SQLExample.getAllColumns();
    SQLExample.closeConnection();
  } 

  public EssentialJDBC() {
    try {
      Class.forName("COM.cloudscape.core.JDBCDriver");
      connection = DriverManager.getConnection(sourceURL);
      statement = connection.createStatement();
    } catch (SQLException sqle) {
      System.err.println("Error creating connection");
    } catch (ClassNotFoundException cnfe) {
      System.err.println(cnfe.toString());
    } 
  }

  void getResultsByColumnName() {

    // Execute wildcard query and output selected columns...
    try {
      ResultSet recordingResults = statement.executeQuery(queryWildcard);
      int row = 0;

      while (recordingResults.next()) {
        System.out.println("Row " + (++row) + ") " 
                           + recordingResults.getString("recordingid") 
                           + " " 
                           + recordingResults.getString("recordingtitle") 
                           + " , " 
                           + recordingResults.getString("catalognumber"));
      }

      recordingResults.close();
    } catch (SQLException sqle) {
      System.err.println("\nSQLException-------------------\n");
      System.err.println("SQLState: " + sqle.getSQLState());
      System.err.println("Message : " + sqle.getMessage());
    } 

  } 

  void getResultsByColumnPosition() {

    // Execute ID and name query and output results...
    try {
      ResultSet recordingResults = statement.executeQuery(queryIDAndName);

      int row = 0;
      while (recordingResults.next()) {
        System.out.print("\nRow " + (++row) + ") ");
        for (int i = 1; i <= 3; i++) {
          System.out.print((i > 1 ? ", " : " ") 
                           + recordingResults.getString(i));
        }
      } 
      recordingResults.close();   // Close the result set
    } catch (SQLException ex) {
      System.err.println("\nSQLException-------------------\n");
      System.err.println("SQLState: " + ex.getSQLState());
      System.err.println("Message : " + ex.getMessage());
    } 

  } 

  void getAllColumns() {

    // Execute wildcard query and output all columns...
    try {
      ResultSet recordingResults = statement.executeQuery(queryWildcard);

      ResultSetMetaData metadata = recordingResults.getMetaData();
      int columns = metadata.getColumnCount();   // Column count
      int row = 0;
      while (recordingResults.next()) {
        System.out.print("\nRow " + (++row) + ") ");
        for (int i = 1; i <= columns; i++) {
          System.out.print((i > 1 ? ", " : " ") 
                           + recordingResults.getString(i));
        }
      } 

      recordingResults.close();                  // Close the result set
    } catch (SQLException ex) {
      System.err.println("\nSQLException-------------------\n");
      System.err.println("SQLState: " + ex.getSQLState());
      System.err.println("Message : " + ex.getMessage());
    } 

  } 

  // Close the connection
  void closeConnection() {
    if (connection != null) {
      try {
        connection.close();
        connection = null;
      } catch (SQLException ex) {
        System.out.println("\nSQLException-------------------\n");
        System.out.println("SQLState: " + ex.getSQLState());
        System.out.println("Message : " + ex.getMessage());
      } 
    } 
  }

  Connection connection;
  Statement statement;
  String sourceURL = "jdbc:cloudscape:Wrox4370.db";
  String queryIDAndName = 
    "SELECT recordingid, recordingtitle, catalognumber FROM recordings";
  String queryWildcard = "SELECT * FROM recordings";   // Select all columns
}