个人中心
文章发布
退出
作者热门文章
- html - 出于某种原因，IE8 对我的 Sass 文件中继承的 html5 CSS 不友好？
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景？
26
4
我想弄清楚为什么这个查询没有使用索引(所以它很长)。
explain select count(*) as aggregate
from `megabase_sms_data_1`
left join `megabase_sms_thematic_repulse_1`
on `megabase_sms_data_1`.`contact_id` = `megabase_sms_thematic_repulse_1`.`megabase_data_id`
where not (megabase_sms_thematic_repulse_1.thematic_id <=> 6)
and `age` in ('2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12', '-1');
+------+-------------+---------------------------------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+---------+-------------------------------------------+----------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+---------------------------------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+---------+-------------------------------------------+----------+-------------+
| 1 | SIMPLE | megabase_sms_data_1 | ALL | tmp_megabase_sms_data_1_age_index,tmp_megabase_sms_data_1_age_incomes_index,tmp_megabase_sms_data_1_age_housing_zipcode_sex_index,tmp_megabase_sms_data_1_age_zipcode_type_sex_index,tmp_megabase_sms_data_1_age_family_zipcode_sex_index,tmp_megabase_sms_data_1_age_couple_zipcode_sex_index,tmp_megabase_sms_data_1_age_department_sex_housing_index,tmp_megabase_sms_data_1_age_type_department_sex_index,tmp_megabase_sms_data_1_age_family_department_sex_index,tmp_megabase_sms_data_1_age_sex_couple_department_index | NULL | NULL | NULL | 20508191 | Using where |
| 1 | SIMPLE | megabase_sms_thematic_repulse_1 | ref | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index | 8 | adsconsole.megabase_sms_data_1.contact_id | 1 | Using where |
我试图将索引添加到 contact_id 上的表，但它没有使用它。可能是我误解了一些概念。
我有那两个表:
DESCRIBE megabase_sms_data_1;
+----------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------------+------------------+------+-----+---------+----------------+
| contact_id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| sms_md5 | varchar(255) | NO | MUL | NULL | |
| sms | varchar(255) | NO | MUL | NULL | |
| age | tinyint(4) | NO | MUL | NULL | |
| sex | tinyint(4) | NO | MUL | NULL | |
| couple | tinyint(4) | NO | MUL | NULL | |
| family | tinyint(4) | NO | MUL | NULL | |
| type | tinyint(4) | NO | MUL | NULL | |
| housing | tinyint(4) | NO | MUL | NULL | |
| gather_date | date | NO | | NULL | |
| freshness_date | date | NO | | NULL | |
| zipcode | char(5) | NO | MUL | NULL | |
| department | char(2) | NO | MUL | NULL | |
| address | varchar(255) | NO | | NULL | |
| city | varchar(255) | NO | | NULL | |
| latitude | double | NO | | NULL | |
| longitude | double | NO | | NULL | |
| incomes | tinyint(4) | NO | MUL | NULL | |
| csp | tinyint(4) | NO | | NULL | |
| adr_iris | varchar(255) | NO | | NULL | |
| adr_inse | varchar(255) | NO | | NULL | |
+----------------+------------------+------+-----+---------+----------------+
21 rows in set (0.00 sec)
SHOW INDEX FROM megabase_sms_data_1;
+---------------------+------------+----------------------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ ---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------+------------+----------------------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ ---------------+
| megabase_sms_data_1 | 0 | PRIMARY | 1 | contact_id | A | 20508191 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 0 | tmp_megabase_sms_data_1_contact_id | 1 | contact_id | A | 20508191 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_sms_md5_index | 1 | sms_md5 | A | 20508191 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_sex_index | 1 | sex | A | 3 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_couple_index | 1 | couple | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_family_index | 1 | family | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_type_index | 1 | type | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_housing_index | 1 | housing | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_incomes_index | 1 | incomes | A | 10 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_incomes_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_incomes_index | 2 | incomes | A | 131 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_type_age_index | 1 | type | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_type_age_index | 2 | age | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_couple_age_index | 1 | couple | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_couple_age_index | 2 | age | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_family_age_index | 1 | family | A | 2 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_family_age_index | 2 | age | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_sex_age_index | 1 | sex | A | 3 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_sex_age_index | 2 | age | A | 52 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_incomes_age_index | 1 | incomes | A | 10 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_incomes_age_index | 2 | age | A | 131 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_sex_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_sex_index | 2 | sex | A | 43266 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_age_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_age_index | 2 | age | A | 110259 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_couple_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_couple_index | 2 | couple | A | 37085 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_family_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_family_index | 2 | family | A | 38261 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_type_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_type_index | 2 | type | A | 38549 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_housing_index | 1 | zipcode | A | 21497 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_zipcode_housing_index | 2 | housing | A | 38841 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_sex_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_sex_index | 2 | sex | A | 396 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_age_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_age_index | 2 | age | A | 1393 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_couple_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_couple_index | 2 | couple | A | 299 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_family_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_family_index | 2 | family | A | 299 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_type_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_type_index | 2 | type | A | 299 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_housing_index | 1 | department | A | 99 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_department_housing_index | 2 | housing | A | 299 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index | 2 | housing | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index | 3 | zipcode | A | 253187 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index | 4 | sex | A | 539689 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index | 2 | zipcode | A | 110259 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index | 3 | type | A | 256352 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index | 4 | sex | A | 554275 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index | 2 | family | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index | 3 | zipcode | A | 256352 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index | 4 | sex | A | 554275 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index | 2 | couple | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index | 3 | zipcode | A | 250099 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index | 4 | sex | A | 525851 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_department_sex_housing_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_department_sex_housing_index | 2 | department | A | 1393 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_department_sex_housing_index | 3 | sex | A | 5067 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_department_sex_housing_index | 4 | housing | A | 12192 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_type_department_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_type_department_sex_index | 2 | type | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_type_department_sex_index | 3 | department | A | 3913 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_type_department_sex_index | 4 | sex | A | 12207 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_department_sex_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_department_sex_index | 2 | family | A | 39 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_department_sex_index | 3 | department | A | 3931 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_family_department_sex_index | 4 | sex | A | 11759 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_sex_couple_department_index | 1 | age | A | 13 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_sex_couple_department_index | 2 | sex | A | 52 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_sex_couple_department_index | 3 | couple | A | 132 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_age_sex_couple_department_index | 4 | department | A | 10868 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | tmp_megabase_sms_data_1_sms_index | 1 | sms | A | 6836063 | NULL | NULL | | BTREE | | |
| megabase_sms_data_1 | 1 | contact_id | 1 | contact_id | A | 20508191 | NULL | NULL | | BTREE | | |
第二个:
describe megabase_sms_thematic_repulse_1;
+------------------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------+------------+------+-----+---------+-------+
| megabase_data_id | bigint(20) | NO | MUL | NULL | |
| thematic_id | int(11) | NO | MUL | NULL | |
+------------------+------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
SHOW INDEX FROM megabase_sms_thematic_repulse_1;
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| megabase_sms_thematic_repulse_1 | 1 | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index | 1 | megabase_data_id | A | 3 | NULL | NULL | | BTREE | | |
| megabase_sms_thematic_repulse_1 | 1 | tmp_megabase_sms_thematic_repulse_1_thematic_id_index | 1 | thematic_id | A | 1 | NULL | NULL | | BTREE | | |
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
我做错了什么？我可以做些什么来优化查询或数据库结构？
非常感谢
最佳答案
根据查询返回的行数，mysql 可能估计使用全扫描比使用索引更有效。
要缩小原因范围，请运行不带 where 子句的查询并查看是否正在使用索引。然后一个一个的加上where子句，看是哪一个导致索引不能用。该 where 子句可能过于通用 - 使其更有效地进行全表扫描，而不是使用索引。
如果假设年龄导致索引无法使用，您可以在 contact_id + age 上创建索引。
关于indexing - Mariadb:为什么我的查询没有使用索引？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48719673/
26
4
0
我在网上搜索但没有找到任何合适的文章解释如何使用 javascript 使用 WCF 服务，尤其是 WebScriptEndpoint。 任何人都可以对此给出任何指导吗？ 谢谢 最佳答案 这是一篇关于
我正在编写一个将运行 Linux 命令的 C 程序，例如: cat/etc/passwd | grep 列表 |剪切-c 1-5 我没有任何结果 *这里 parent 等待第一个 child (chi
所以我正在尝试处理文件上传，然后将该文件作为二进制文件存储到数据库中。在我存储它之后，我尝试在给定的 URL 上提供文件。我似乎找不到适合这里的方法。我需要使用数据库，因为我使用 Google 应用引
我正在尝试制作一个宏，将下面的公式添加到单元格中，然后将其拖到整个列中并在 H 列中复制相同的公式 我想在 F 和 H 列中输入公式的数据 Range("F1").formula = "=IF(ISE
问题类似于this one ，但我想使用 OperatorPrecedenceParser 解析带有函数应用程序的表达式在 FParsec . 这是我的 AST: type Expression =
我想通过使用 sequelize 和 node.js 将这个查询更改为代码取决于在哪里 select COUNT(gender) as genderCount from customers where
我正在使用GNU bash，版本5.0.3(1)-发行版(x86_64-pc-linux-gnu)，我想知道为什么简单的赋值语句会出现语法错误: #/bin/bash var1=/tmp
这里，为什么我的代码在 IE 中不起作用。我的代码适用于所有浏览器。没有问题。但是当我在 IE 上运行我的项目时，它发现错误。 而且我的 jquery 类和 insertadjacentHTMl 也不
我正在尝试更改标签的innerHTML。我无权访问该表单，因此无法编辑 HTML。标签具有的唯一标识符是“for”属性。 这是输入和标签的结构:
我有一个页面，我可以在其中返回用户帖子，可以使用一些 jquery 代码对这些帖子进行即时评论，在发布新评论后，我在帖子下插入新评论以及删除 按钮。问题是 Delete 按钮在新插入的元素上不起作用，
我有一个大约有 20 列的“管道分隔”文件。我只想使用 sha1sum 散列第一列，它是一个数字，如帐号，并按原样返回其余列。 使用 awk 或 sed 执行此操作的最佳方法是什么？ Accounti
我需要将以下内容插入到我的表中...我的用户表有五列 id、用户名、密码、名称、条目。 (我还没有提交任何东西到条目中，我稍后会使用 php 来做)但由于某种原因我不断收到这个错误:#1054 - U
所以我试图有一个输入字段，我可以在其中输入任何字符，但然后将输入的值小写，删除任何非字母数字字符，留下“。”而不是空格。 例如，如果我输入: 地球的 70% 是水，-!*#$^^ & 30% 土地 输
我正在尝试做一些我认为非常简单的事情，但出于某种原因我没有得到想要的结果？我是 javascript 的新手，但对 java 有经验，所以我相信我没有使用某种正确的规则。 这是一个获取输入值、检查选择
我想使用 angularjs 从 mysql 数据库加载数据。 这就是应用程序的工作原理；用户登录，他们的用户名存储在 cookie 中。该用户名显示在主页上 我想获取这个值并通过 angularjs
我正在使用 autoLayout，我想在 UITableViewCell 上放置一个 UIlabel，它应该始终位于单元格的右侧和右侧的中心。 这就是我想要实现的目标 所以在这里你可以看到我正在谈论的
我需要与 MySql 等效的 elasticsearch 查询。我的 sql 查询: SELECT DISTINCT t.product_id AS id FROM tbl_sup_price t
我正在实现代码以使用 JSON。 func setup() { if let flickrURL = NSURL(string: "https://api.flickr.com/
我尝试使用for循环声明变量，然后测试cols和rols是否相同。如果是，它将运行递归函数。但是，我在 javascript 中执行 do 时遇到问题。有人可以帮忙吗？ 现在，在比较 col.1 和
我举了一个我正在处理的问题的简短示例。 HTML代码: 1 2 3 CSS 代码: .BB a:hover{ color: #000; } .BB > li:after {
我是一名优秀的程序员,十分优秀！