Code listing 11.1 TeamDB.java
import java.util.Scanner;
import java.sql.*;
/**
 This program uses a database to keep track of summer T-ball
 teams, games, and season records.
*/
public class TeamDB
{
 public static void main(String[] args)
 {
 // Create a named constant for the URL
 // NOTE: This value is specific for Java DB
 final String DB_URL = "jdbc:derby:TeamDB;create=true";
 Connection conn;
 try
 {
 // Create a connection to the database
 conn = DriverManager.getConnection(DB_URL);
 char choice;
 Scanner keyboard = new Scanner(System.in);
 System.out.println("Welcome to the Sports " +
 "Teams Database Manager!");
 do
 {
 printMenu();
 choice = keyboard.nextLine().charAt(0);
 switch(choice)
 {
 case '0':
 // Close the connection
conn.close();
break;
 case '1':
 viewTeams(conn);
break;
 case '2':
 viewSchedule(conn);
break;
 case '3':
 addTeams(conn);
break;
 case '4':
 addGames(conn);
break;
 case '5':
 enterScores(conn);
 break;
 case '6':
 beginNewSeason(conn);
break;
 }
 } while(choice != '0');
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The printMenu method displays the menu choices
 for the user to work with the database.
 */
 public static void printMenu()
 {
 System.out.println();
 System.out.println("Select from the following options:");
 System.out.println("1. View team standings");
 System.out.println("2. View the schedule");
 System.out.println("3. Add a team");
 System.out.println("4. Add a game to the schedule");
 System.out.println("5. Enter game scores");
 System.out.println("6. Begin a new season");
 System.out.println("0. Exit the program");
 }
 /**
 The beginNewSeason method is a utility method that
 removes the tables and allows the user to reset the
 database for a new season.
 @param conn A connection to the database.
 */
 public static void beginNewSeason(Connection conn)
 {
 try
 {
 Statement stmt = conn.createStatement();
 // Remove tables if database tables have been created.
 // This will throw an exception if the tables do not exist
 stmt.execute("DROP TABLE Games");
 stmt.execute("DROP TABLE Teams");
 // Once the tables have been removed, call the method to
 // create and initialize the tables
 System.out.println("Reinitializing database " +
 "for a new season");
 createTeamDB(conn);
 }
 catch(Exception ex)
 {
 // Call the method to create tables for the database
 System.out.println("Creating database for the first time");
 createTeamDB(conn);
 }
 }
 /**
 The createTeamDB method is a utility method that
 creates the tables and initializes the database
 with teams and games.
 @param conn A connection to the database.
 */
 public static void createTeamDB(Connection conn)
 {
 try
 {
 Statement stmt = conn.createStatement();
 // Create the table of teams
 stmt.execute("CREATE TABLE Teams (" +
 "TeamName CHAR(15) NOT NULL PRIMARY KEY, " +
"Wins INT, " + "Losses INT, " +
"Ties INT" + ")");
 // Add some teams
 stmt.executeUpdate("INSERT INTO Teams " +
 "(TeamName) " +
"VALUES ('Astros')");
 stmt.executeUpdate("INSERT INTO Teams " +
 "(TeamName) " +
 "VALUES ('Marlins')");
 stmt.executeUpdate("INSERT INTO Teams " +
 "(TeamName) " +
"VALUES ('Brewers')");
 stmt.executeUpdate("INSERT INTO Teams " +
 "(TeamName) " +
"VALUES ('Cubs')");
 // Create a listing of the games to be played
 stmt.execute("CREATE TABLE Games (" +
 "GameNumber INT NOT NULL PRIMARY KEY, " +
"HomeTeam CHAR(15) NOT NULL REFERENCES " +
"Teams (TeamName), " +
"HomeTeamScore INT, " +
"VisitorTeam CHAR(15) NOT NULL " +
 "REFERENCES Teams (TeamName), " +
 "VisitorTeamScore INT" + ")");
 stmt.executeUpdate("INSERT INTO Games " +
 "(GameNumber, HomeTeam, VisitorTeam) " +
"VALUES (1, 'Astros', 'Brewers')");
 stmt.executeUpdate("INSERT INTO Games " +
 "(GameNumber, HomeTeam, VisitorTeam) " +
"VALUES (2, 'Brewers', 'Cubs')");
 stmt.executeUpdate("INSERT INTO Games " +
 "(GameNumber, HomeTeam, VisitorTeam) " +
"VALUES (3, 'Cubs', 'Astros')");
 }
 catch (Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The addTeams method allows the user to add
 more teams to the database.
 @param conn A connection to the database.
 */
 public static void addTeams(Connection conn)
 {
 Scanner keyboard = new Scanner(System.in);
 try
 {
 char ans;
 String teamName;
 Statement stmt = conn.createStatement();
 do
 {
 // TASK #3
 // Prompt the user for a new team name
 // Write SQL statement and update the Teams table
 System.out.print("Do you want to enter another team: ");
 ans = keyboard.nextLine().charAt(0);
 } while(ans == 'Y'|| ans == 'y');
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The addGames method allows the user to add games to the
 schedule. A unique game number is created for each game
 on the schedule.The user will need to supply a home team
 name and a visitor team name from the keyboard.
 @param conn A connection to the database.
 */
 public static void addGames(Connection conn)
 {
 Scanner keyboard = new Scanner (System.in);
 try
 {
 char ans;
 String homeTeam;
 String visitingTeam;
 int gameNumber = 1;
 Statement stmt = conn.createStatement();
 // This retrieves the data and allows you to count
 // the number of games already scheduled so that you
 // add a unique game number
 String sqlStatement = "SELECT * from Games";
 ResultSet result = stmt.executeQuery(sqlStatement);
 while(result.next())
 {
 gameNumber++;
 }
 do
 {
 System.out.print("Enter the home team name: ");
 homeTeam = keyboard.nextLine();
 System.out.print("Enter the visiting team name: ");
 visitingTeam = keyboard.nextLine();
 sqlStatement = "INSERT INTO Games " +
 "(GameNumber, HomeTeam, VisitorTeam) " +
"VALUES (" + gameNumber + ", '" +
homeTeam + "', '" + visitingTeam + "')";
 stmt.executeUpdate(sqlStatement);
 System.out.print("Do you want to enter another game: ");
 ans = keyboard.nextLine().charAt(0);
 } while(ans == 'Y'|| ans == 'y');
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The viewTeams method displays a table listing the
 team names and season records. Since teams have not
 yet played, all numbers are zero.
 @param conn A connection to the database.
 */
 public static void viewTeams(Connection conn)
 {
 try
 {
 // Create a Statement object
 Statement stmt = conn.createStatement();
 // Create a string with a SELECT statement
 String sqlStatement = "SELECT * FROM Teams";
 // Send the statement to the DBMS
 ResultSet result = stmt.executeQuery(sqlStatement);
 System.out.printf("%-15s %10s %10s %10s\n",
 "Team Name", "Win", "Lose",
 "Tie");
 // Display the contents of the result set
 // The result set will have 5 columns
 while(result.next())
 {
 System.out.printf("%-15s %10d %10d %10d\n",
 result.getString("TeamName"),
result.getInt("Wins"),
result.getInt("Losses"),
result.getInt("Ties"));
 }
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The viewSchedule method retrieves and displays the
 teams and scores for all games.
 @param conn A connection to the database.
 */
 public static void viewSchedule(Connection conn)
 {
 try
 {
 // Create a Statement object
 Statement stmt = conn.createStatement();
 // TASK #2
 // Create a string with a SELECT statement
 // Send the statement to the DBMS
 // This is a suggested column headings display
 System.out.println("List of games and scores:");
 System.out.printf("%-6s %-20s %6s %-20s %6s\n",
 "GameID", "Home", "Score",
"Visitor", "Score");
 // TASK #2
 // Use a while loop to display the result set
 // The result set will have five columns
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
 /**
 The enterScores method allows user to enter scores for both
 teams. The method will update the Games table with the scores
 entered. It will also compare the scores to determine the
 winning and losing teams (or tie) and update the appropriate
 column in the Teams table for each team involved in the game.
 @param conn A connection to the database.
 */
 public static void enterScores(Connection conn)
 {
 Scanner keyboard = new Scanner(System.in);
 try
 {
 char ans;
 int gameNumber;
 String homeTeam;
 String visitingTeam;
 int score1;
 int score2;
 String sqlStatement;
 ResultSet result;
 Statement stmt = conn.createStatement();
 do
 {
 viewSchedule(conn);
 System.out.print("Enter the game ID: ");
 gameNumber = keyboard.nextInt();
 // TASK #4
 // Get the result set from a query that selects all
 // information for the gameNumber the user entered
 if(result.next())
 {
 homeTeam = result.getString("HomeTeam");
 visitingTeam = result.getString("VisitorTeam");
 System.out.print("Enter the score for the " +
 homeTeam);
 score1 = keyboard.nextInt();
 System.out.print("Enter the score for the " +
 visitingTeam);
 score2 = keyboard.nextInt();
 keyboard.nextLine();
 // TASK #4
 // Execute an update to the Games table to
 // store the score for each team of that
 // game number
 if(score1 < score2)
 {
 // TASK #4
// Retrieve the number from the appropriate column
// (wins, losses, or ties) for the home team,
 // increment, and update that team's record.
 // Do the same for the visiting team
 }
 else if(score2 < score1)
 {
 // TASK #4
// Retrieve the number from the appropriate column
// (wins, losses, or ties) for the home team,
// increment, and update that team's record.
// Do the same for the visiting team
 }
 else
 {
 // TASK #4
// Retrieve the number from the appropriate column
// (wins, losses, or ties) for the home team,
// increment, and update that team's record.
// Do the same for the visiting team
 }
 }
 System.out.print("Do you want to enter another game: ");
 ans = keyboard.nextLine().charAt(0);
 } while(ans == 'Y'|| ans == 'y');
 }
 catch(Exception ex)
 {
 System.out.println("ERROR: " + ex.getMessage());
 }
 }
}