complexquery.java

来自「beginJsp2.0外文书籍源代码」· Java 代码 · 共 51 行

package com.wrox.library;
import javax.naming.*;
import javax.sql.*;
import java.sql.*;

public class ComplexQuery {
  Connection conn;
  public ComplexQuery() { }
  public void connect() {
    try{
      Context ctx = new InitialContext();
      if(ctx == null )
          throw new Exception("Oops - No Context");

      DataSource ds =
            (DataSource)ctx.lookup(
               "java:comp/env/jdbc/BooksDB");

      if (ds != null)
        conn = ds.getConnection();
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  public void disconnect() {
    try {
      if ( conn != null ) {
        conn.close();
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  public ResultSet viewBooks() {
    ResultSet rs = null;
    try {
      Statement stmt = conn.createStatement();
      rs = stmt.executeQuery
            ("SELECT Book.Title_ID, Book.Title, Book.Price," +
             "Category.Category_Description AS Category " +
             "FROM Book, Category " +
             "WHERE Book.Category_ID = Category.Category_ID " +
             "ORDER BY Category, Book.Price DESC;");

    } catch (Exception e) {
      e.printStackTrace();
    }
    return rs;
  }
}