java - 对多个数据库使用单个 JDBC 连接

Question

我有一个到 SQLite 数据库的 JDBC 连接。从第一个数据库 (productLine.db) 获取信息后，我想将连接切换到 shipMethods.db 并从该数据库读取一个表。我目前收到错误:

    SQL error or missing database (no such table: Ground)

我检查了数据库，表就在那里。我需要创建一个新的连接变量还是我做错了什么？

代码如下:

    //Get connection to database
    try {
        Connection con = DriverManager.getConnection ("jdbc:sqlite:productLine.db");
        //Make statement for interacting with database
        Statement stmt = con.createStatement();

        //Get total weight
        ResultSet rs = stmt.executeQuery ("SELECT Weight FROM Numbers WHERE TYPE = '" + product + "'");
        while (rs.next()) {
            weight = rs.getDouble("weight")*1000;
        }

        //get zone
        rs = stmt.executeQuery ("SELECT ZONE FROM Zones WHERE ZIP = " + shortZip);
        while (rs.next()) {
            zone = rs.getInt("Zone");
        }

        //Change to Ship Methods database
        con = DriverManager.getConnection("jdbc:sqlite:shipMethods.db");

        //Get Price
        rs = stmt.executeQuery ("SELECT EIGHT FROM Ground WHERE WEIGHT = " + weight);
        while (rs.next()) {
            price = rs.getDouble("Cost");
        }

        System.out.println("Weight: " + weight);
        System.out.println("Zone: " + zone);
        System.out.println("Price: " + price);

    } catch(SQLException e) {
        System.out.println("SQL exception occured" + e);
    }

Answer 1

您正在使用的语句 属于旧连接。(您有两个 Activity 连接；否则计算机应该如何知道使用哪一个？)

从新连接创建新语句。