Java:在同一个类中创建Mysql数据库和表

Question

我正在创建一个用于创建 MySQL 数据库和表的 Java 程序。我是相当新的，所以我边走边学。我能够创建数据库，然后继续创建表。当我运行我的程序时，我得到了这个异常错误

java.sql.SQLException: No database selected

我明白我遇到的错误，但我不知道当我已经将我的 URL 设置到我的根目录时我可以选择数据库。

String url = "jdbc:mysql://localhost:3306/";

下面是我的代码，欢迎任何反馈，谢谢。

import java.sql.Connection;
import java.sql.Statement;
import java.sql.DriverManager;
import java.sql.SQLException;


public class MysqlSetUp{

private static final String EMPLOYEE_TABLE = "create table MyEmployees3 ( "
  + "   id INT PRIMARY KEY, firstName VARCHAR(20), lastName VARCHAR(20), "
  + "   title VARCHAR(20), salary INT )";

public static Connection getConnection() throws Exception {
String driver = "org.gjt.mm.mysql.Driver";
String url = "jdbc:mysql://localhost:3306/";
String username = "root";
String password = "";
Class.forName(driver);
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
}
  public static void main(String args[]) {
  Connection conn = null;
  Statement stmt = null;
  try {
    conn = getConnection();
    stmt = conn.createStatement();
    stmt.executeUpdate("CREATE DATABASE Employess");
    stmt.executeUpdate(EMPLOYEE_TABLE);
    stmt.executeUpdate("insert into MyEmployees3(id, firstName) values(100, 'A')");
    stmt.executeUpdate("insert into MyEmployees3(id, firstName) values(200, 'B')");
    System.out.println("CreateEmployeeTableMySQL: main(): table created.");
      } catch (ClassNotFoundException e) {
    System.out.println("error: failed to load MySQL driver.");
    e.printStackTrace();
  } catch (SQLException e) {
    System.out.println("error: failed to create a connection object.");
    e.printStackTrace();
  } catch (Exception e) {
    System.out.println("other error:");
    e.printStackTrace();
  } finally {
    try {
      stmt.close();
      conn.close();
    } catch (SQLException e) {
      e.printStackTrace();
     }
   }
  }
 }

Answer 1

创建后您需要USE Employess。

...
stmt = conn.createStatement();
stmt.executeUpdate("CREATE DATABASE Employess");
stmt.executeUpdate("USE Employess");
stmt.executeUpdate(EMPLOYEE_TABLE);
...