java连接数据库，实现删除库表数据

    public void connect() {        Connection conn = null;        Statement statement = null;        ResultSet resultSet = null;        try {            Class.forName("com.mysql.jdbc.Driver");            String url = "jdbc:mysql://127.0.0.1:3306/cl";            String user = "root";            String password = "5201314";            conn = DriverManager.getConnection(url, user, password);            DatabaseMetaData batabaseData = conn.getMetaData();//DatabaseMetaData关于数据库的整体综合信息            String catalog = conn.getCatalog();//catelog目录名称            resultSet = batabaseData.getTableTypes();//表类型            String[] types = {"TABLE"};            resultSet = batabaseData.getTables(catalog, batabaseData.getUserName(), "%", types);            while (resultSet.next()) {                String tableName = resultSet.getString("TABLE_NAME");                String sql = "DELETE FROM " + tableName;                statement=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);            }

// 获取可在给定类别中使用的表的描述。仅返回与类别、模式、表名称和类型标准匹配的表描述。//            它们根据 TABLE_TYPE、TABLE_CAT、TABLE_SCHEM 和 TABLE_NAME 进行排序。//每个表描述都有以下列：//TABLE_CAT String => 表类别（可为 null）//TABLE_SCHEM String => 表模式（可为 null）//TABLE_NAME String => 表名称//TABLE_TYPE String => 表类型。典型的类型是 "TABLE"、"VIEW"、"SYSTEM TABLE"、"GLOBAL TEMPORARY"、"LOCAL TEMPORARY"、"ALIAS" 和 "SYNONYM"。//REMARKS String => 表的解释性注释//TYPE_CAT String => 类型的类别（可为 null）//TYPE_SCHEM String => 类型模式（可为 null）//TYPE_NAME String => 类型名称（可为 null）//SELF_REFERENCING_COL_NAME String => 有类型表的指定 "identifier" 列的名称（可为 null）//REF_GENERATION String => 指定在 SELF_REFERENCING_COL_NAME 中创建值的方式。这些值为 "SYSTEM"、"USER" 和 "DERIVED"。（可能为 null）//            resultSet = statement.executeQuery("select * FROM yonghu");

            JOptionPane.showMessageDialog(null, "确认删除");//            ResultSetMetaData resultSetMetaData = resultSet.getMetaData();//            while (resultSet.next()) {  // ResultSet指针指向下一个“行”//                System.out.println(resultSet.getInt("No")//                        + "/t" + resultSet.getString("Name"));//            }

        } catch (Exception ex) {            ex.printStackTrace();        }    }