java - JDBC 找不到正确的 MySql 数据库

Question

当我运行此代码以连接到数据库并添加对象时

import java.sql.*;
import java.util.Scanner;

import java.sql.*;
import java.util.Scanner;

public class Driver {
public static void main(String [] args) {
    try {
        //Get connection to DB
        Connection myConn = DriverManager.getConnection("jdbc:mysql://LocalHost:3306/interndata?useSSL=false" , "root" , "Starwars991211");
        //Create a statement 
        Statement myStmt = myConn.createStatement();

        Scanner scan = new Scanner(System.in);

        int entryNum, citNum ;
        String date, score ;
        String keepGoing = "y";

        while (keepGoing.equals("y") || keepGoing.equals("Y")){
            System.out.println("Enter the id");
            entryNum = scan.nextInt(); 
            System.out.println("Enter the date");
            date = scan.next(); 
            System.out.println("Enter the citnum");
            citNum = scan.nextInt(); 
            System.out.println("Enter the score");
            score = scan.next(); 
            String sql = "INSERT INTO employee (EntryNumber, Date, ``CriterionNum, Score)"   + " values (?, ?, ?, ?)";
            PreparedStatement preparedStatement = myConn.prepareStatement(sql);
            preparedStatement.setInt(1, entryNum);
            preparedStatement.setString(2, date);
            preparedStatement.setInt(3,citNum);
            preparedStatement.setString(4, score);
            preparedStatement.executeUpdate(); 
            System.out.print("Another factorial? (y/n) ");
            keepGoing = scan.next();
        }           
        //Execute SQL query
        ResultSet myRs = myStmt.executeQuery("select * from teacherexample");
        //process result set
        while (myRs.next()) {
            System.out.println("ID: " + myRs.getInt("EntryNumber") + " Name: " + myRs.getString("Date") + ", " + myRs.getInt("CriterionNum") + "  " +  myRs.getString("Score"));
        }
    }
    catch (Exception exc) {
        exc.printStackTrace();
    }
}
}

我收到此错误

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'interndata.employee' doesn't exist

internexample.employee 是在我更改名称之前 interndata.teacherexample 的名称。

我的问题是，即使代码中没有提及，为什么程序仍然尝试连接到不存在的旧数据库？

Answer 1

why is the program still trying to connect to the older database that does not exist

在您的 JDBC 字符串中，您已将数据库名称指定为 interndata

jdbc:mysql://LocalHost:3306/interndata

因此，以下任何查询 INSERT 或 SELECT 都将在 interndata 数据库上下文下执行。

所以，当您执行以下查询时

INSERT INTO employee ...

它将针对 interndata 数据库中的 employee 表执行。如果您想在不同的数据库上下文(即 internexample)中执行上述查询。然后，您需要将 JDBC 字符串更改为

jdbc:mysql://LocalHost:3306/internexample