Question

我正在开展一个学校项目，我必须与访问数据库进行交互。我正试图

SELECT Max(GameID) AS MaxID
FROM Games

但是，当我构建的Eclipse应用程序运行时，此查询仅在控制台中返回

SQL Exception: UCAExc:::4.0.3 Column not found: GameID
SQL State: S1000
Vendor Error: -421

我检查了访问数据库和列DEFINITELY EXISTS。我在访问数据库中运行了查询，它也在那里工作。我不确定我错过了什么，或者这是否可能。我怎样才能获得gameID的最高价值？

这是与数据库的连接

ResultSet rs = null; //will hold record that get returned
Statement stmt = null; //will hold the SQL statement we want to run

try
{
    //2. Establish the connection
    Connection conn = DriverManager.getConnection("jdbc:ucanaccess://C:/Users/Public/ZaccaroBlottoDB.accdb");

    //3. Create the statement
    stmt = conn.createStatement();
    String theQuery = "SELECT Max(" 
            + "GameID)"
            + " As MaxID"
            + " FROM Games"
            + " WHERE (1=1)";

    //4. Execute the statement
    rs = stmt.executeQuery(theQuery);

    //5. Process the results
    while (rs.next())
    {
        int gameID = rs.getInt("GameID"); //note the type and the field name from the DB


        System.out.println(gameID);
        //addGameIDFTF.setText(Integer.toString(gameID +1));
    }//while

    //6. Close the Connection
    rs.close();
    conn.close();           
} 
catch (SQLException ex)
{
    System.out.println("SQL Exception: " + ex.getMessage());
    System.out.println("SQL State: " + ex.getSQLState());
    System.out.println("Vendor Error: " + ex.getErrorCode());
    ex.printStackTrace();
} //catch

Answer 1

我认为问题在于您正在检索的价值。正如您所提到的别名是MaxID，您应该从result_set获取MaxID而不是GameID

因此，它应该是

int gameID = rs.getInt("MaxID");

而不是

int gameID = rs.getInt("GameID");

如何在Eclipse中正确使用Select Max（）

1 个答案: