java對sql server的增刪改查

package Database; 
import java.sql.*;
public class DBUtil { 
    //這里可以設置數據庫名稱 
    private final static String URL = "jdbc:sqlserver://127.0.0.1:1433;DatabaseName=mythree"; 
    private static final String USER="sa"; 
    private static final String PASSWORD="123"; 
    private static Connection conn=null; 
    //靜態代碼塊（將加載驅動、連接數據庫放入靜態塊中） 
    static{ 
        try { 
    
        //1.加載驅動程序
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
        //2.獲得數據庫的連接
            conn=(Connection)DriverManager.getConnection(URL,USER,PASSWORD); 
        } 
        catch (ClassNotFoundException e) {
            e.printStackTrace(); 
        } catch (SQLException e) {
            e.printStackTrace(); 
        }
    } 
    //對外提供一個方法來獲取數據庫連接
    public static Connection getConnection(){
        return conn; 
    }
    //查詢
    public void select(Statement stmt) throws SQLException {
        ResultSet rs = stmt.executeQuery("select * from  李運辰.選課"); 
           while(rs.next()){
               //如果對象中有數據，就會循環打印出來
               System.out.println("學號="+rs.getInt("學號")+"課程編號="+rs.getInt("課程編號")+"考試成績="+rs.getInt("考試成績"));
               
               //System.out.println(rs.getInt("教師編號")+","+rs.getString("姓名")+","+rs.getInt("專業")); 
           } 
    }
    //插入
    public void insert(Statement stmt) throws SQLException {
        //成功-返回false
        boolean execute = stmt.execute("insert into  李運辰.選課   values(1,2,100)");
        System.out.println(execute);
    }
    //更新
    public void update(Statement stmt) throws SQLException {
        //返回序號
        int executeUpdate = stmt.executeUpdate("update   李運辰.選課  set 考試成績=90  where 學號=1 "); 
        System.out.println(executeUpdate);
    }
    //刪除
    public void delete(Statement stmt) throws SQLException {
        //成功-返回false
        boolean execute = stmt.execute("delete from 李運辰.選課 where  學號=11 and 課程編號=2");
        System.out.println(execute);
    }
    //測試用例
    public static void main(String[] args) throws Exception{ 
        DBUtil d = new DBUtil();
        //3.通過數據庫的連接操作數據庫，實現增刪改查 
        Statement stmt = conn.createStatement(); 
        //ResultSet executeQuery(String sqlString)：執行查詢數據庫的SQL語句 ，返回一個結果集（ResultSet）對象。
        //d.insert(stmt);
        //d.update(stmt);
        d.delete(stmt);
        d.select(stmt);
       
     } 
       
       
}