@Test
    public void rrs(){
        try {
            Statement st = conn.createStatement();
            ResultSet rs = st.executeQuery("select id ID,name 姓名,score 成绩 from st 学生");
            ResultSetMetaData rsm = rs.getMetaData();
            System.out.println(rsm.getColumnCount());   //表的列数
            System.out.println(rsm.getTableName(1));    //表名
            for(int i =1; i<=rsm.getColumnCount();i++){
                System.out.println("-".repeat(80));
                System.out.println(rsm.getColumnName(i));   //表的字段名
                System.out.println(rsm.getColumnLabel(i));  //表的别名
                System.out.println(rsm.getColumnType(i));   //列的类型，数字表示
                System.out.println(rsm.getColumnTypeName(i));   //列的类型，字符串表示
                System.out.println(rsm.getCatalogName(i));  //数据库名
            }


        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }

    }