import java.sql.Connection; import java.sql.DriverManager; import java.sql.Statement; public class L43 { public static final String url = "jdbc:mysql://localhost:3306;DatabaseName=yggl"; private final static String username = "root"; private final static String password = "ziyexue"; public static void main(String args[]) { try { Class.forName("com.mysql.cj.jdbc.Driver"); System.out.println("加载驱动成功！"); } catch (Exception e) { e.p rintStackTrace(); System.out.println("OK"); } try { String url="jdbc:mysql://localhost:3306/yggl"+"?useUnicode=true&characterEncoding=UTF-8&userSSL=true&serverTimezone=UTC"; Connection dbConn=DriverManager.getConnection(url, username, password); Statement st= dbConn.createStatement(); System.out.println("连接数据库成功！"); } catch (Exception e) { e.printStackTrace(); System.out.println("SQL Server连接失败！"); } } } 这段代码哪有问题

这段代码有两个问题：

1. 在`url` 变量中，`DatabaseName` 应该改为 `databaseName`，并且连接字符串最后应该加上具体的数据库名，正确的格式应该是 `jdbc:mysql://localhost:3306/yggl`。

2. `e.p rintStackTrace()` 中间的空格应该去掉，正确的写法是 `e.printStackTrace()`。

下面是修改后的代码：

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

public class L43 {
    public static final String url = "jdbc:mysql://localhost:3306/yggl";
    private final static String username = "root";
    private final static String password = "ziyexue";

    public static void main(String args[]) {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            System.out.println("加载驱动成功！");
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("OK");
        }
        try {
            String url = "jdbc:mysql://localhost:3306/yggl" + "?useUnicode=true&characterEncoding=UTF-8&userSSL=true&serverTimezone=UTC";
            Connection dbConn = DriverManager.getConnection(url, username, password);
            Statement st = dbConn.createStatement();
            System.out.println("连接数据库成功！");
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("SQL Server连接失败！");
        }
    }
}