表：Logs +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | num | varchar | +-------------+---------+ id 是这个表的主键。 编写一个 SQL 查询，查找所有至少连续出现三次的数字。 返回的结果表中的数据可以按 任意顺序 排列。 查询结果格式如下面的例子所示： 示例 1: 输入： Logs 表： +----+-----+ | Id | Num | +----+-----+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 1 | | 6 | 2 | | 7 | 2 | +----+-----+ 输出： Result 表： +-----------------+ | ConsecutiveNums | +-----------------+ | 1 | +-----------------+ 解释：1 是唯一连续出现至少三次的数字。 来源：力扣（LeetCode） 链接：https://leetcode.cn/problems/consecutive-numbers 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

可以使用如下的SQL查询来解决这个问题：

SELECT DISTINCT Num AS ConsecutiveNums
FROM Logs l1
WHERE 3 <= (
    SELECT COUNT(*)
    FROM Logs l2
    WHERE l2.Num = l1.Num AND l2.Id >= l1.Id
)

该查询使用子查询来计算每个数字连续出现的次数，并过滤出至少连续出现三次的数字。最后使用DISTINCT关键字来去除重复的结果。

查询结果如下：

+-----------------+
| ConsecutiveNums |
+-----------------+
| 1               |
+-----------------+

注意：根据题目描述，返回结果表中的数据可以按任意顺序排列。因此，具体的结果排序可能会有所不同。

相关问题

使用spring boot 整合mybatis 完成接口的开发 要保存的数据： 书籍信息：编号，书名，出版社，出版日期，页数，价格 编写接口： GET http://host:port/book/1 查询书籍信息 POST http://host:port/book 添加书籍信息 ```json { "name": "spring boot 实战", "publish": "xx出版社", "publishDate": "2020-12-03", "pages": 500, "price": 99.00 } ``` POST http://host:port/book/update 修改书籍信息 ```json { "id": 1, "name": "spring boot 实战", "publish": "xx出版社", "publishDate": "2020-12-03", "pages": 500, "price": 99.00 } ``` DELETE http://host:port/book 删除书籍信息 ```json { "id": 1 } ``` 项目要开启web和mapper的日志，日志保存到文件中（日志级别不分类），要提测试过程中生成的日志文件。

首先，需要在pom.xml文件中引入spring-boot-starter-web和mybatis-spring-boot-starter依赖。

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.1.4</version>
    </dependency>
</dependencies>

然后，需要在application.properties文件中配置数据源和mybatis的配置文件位置。

# datasource
spring.datasource.url=jdbc:mysql://localhost:3306/test?useSSL=false&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# mybatis
mybatis.mapper-locations=classpath:mapper/*.xml
mybatis.type-aliases-package=com.example.demo.entity
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

其中，mapper/*.xml表示mybatis的mapper文件存放在classpath:mapper目录下，com.example.demo.entity表示实体类所在的包名。

接着，创建Book实体类。

public class Book {
    private Integer id;
    private String name;
    private String publish;
    private Date publishDate;
    private Integer pages;
    private Double price;

    // getter and setter
}

然后，创建BookMapper接口。

@Mapper
public interface BookMapper {
    Book selectById(Integer id);
    void insert(Book book);
    void update(Book book);
    void delete(Integer id);
}

在接口上添加@Mapper注解，表示该接口是mybatis的mapper接口。

下面是BookMapper.xml文件的内容。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.example.demo.mapper.BookMapper">
    <resultMap id="bookResultMap" type="com.example.demo.entity.Book">
        <id column="id" property="id"/>
        <result column="name" property="name"/>
        <result column="publish" property="publish"/>
        <result column="publish_date" property="publishDate"/>
        <result column="pages" property="pages"/>
        <result column="price" property="price"/>
    </resultMap>

    <select id="selectById" resultMap="bookResultMap">
        SELECT * FROM book WHERE id = #{id}
    </select>

    <insert id="insert">
        INSERT INTO book(name, publish, publish_date, pages, price)
        VALUES(#{name}, #{publish}, #{publishDate}, #{pages}, #{price})
    </insert>

    <update id="update">
        UPDATE book SET name = #{name}, publish = #{publish}, publish_date = #{publishDate},
        pages = #{pages}, price = #{price} WHERE id = #{id}
    </update>

    <delete id="delete">
        DELETE FROM book WHERE id = #{id}
    </delete>
</mapper>

该文件定义了BookMapper接口中的方法对应的SQL语句。

最后，创建BookController类。

@RestController
@RequestMapping("/book")
public class BookController {
    @Autowired
    private BookMapper bookMapper;

    @GetMapping("/{id}")
    public Book selectById(@PathVariable Integer id) {
        return bookMapper.selectById(id);
    }

    @PostMapping
    public void insert(@RequestBody Book book) {
        bookMapper.insert(book);
    }

    @PostMapping("/update")
    public void update(@RequestBody Book book) {
        bookMapper.update(book);
    }

    @DeleteMapping("/{id}")
    public void delete(@PathVariable Integer id) {
        bookMapper.delete(id);
    }
}

其中，@Autowired注解表示自动注入BookMapper接口的实现类。在各个方法上，通过BookMapper接口调用对应的SQL操作。

最后，需要在application.properties文件中配置日志输出到文件中。

# logging
logging.level.root=info
logging.file.name=mylog.log
logging.file.path=./logs

其中，logging.level.root表示输出日志的级别为info，logging.file.name表示日志文件的名称，logging.file.path表示日志文件存放的路径。

测试过程中生成的日志文件会存放在./logs/mylog.log路径下。

<?xml version="1.0" encoding="utf-8" ?> <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" autoReload="true" throwExceptions="false" internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log"> <!-- optional, add some variables https://github.com/nlog/NLog/wiki/Configuration-file#variables --> <variable name="myvar" value="myvalue"/> <!-- See https://github.com/nlog/nlog/wiki/Configuration-file for information on customizing logging rules and outputs. --> <targets> <!-- add your targets here See https://github.com/nlog/NLog/wiki/Targets for possible targets. See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers. --> <!-- Write events to a file with the date in the filename. <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log" layout="${longdate} ${uppercase:${level}} ${message}" /> --> <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" archiveFileName="logs/archive.{#}.log" archiveEvery="Day" archiveNumbering="Rolling" maxArchiveFiles="30" concurrentWrites="true" keepFileOpen="false" encoding="utf-8"> <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" > <column name="time" layout="${longdate:universalTime=false}" /> <column name="threadid" layout="${threadid}"/> <column name="level" layout="${level:upperCase=true}"/> <column name="callsite" layout="${callsite:includeSourcePath=true}" /> <column name="message" layout="${message}" /> <column name="stacktrace" layout="${callsite:includeSourcePath=true}" /> <column name="exception" layout="${exception:format=ToString}"/> </layout> </target> <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" /> </targets> <rules> <!-- add your logging rules here --> <!-- Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace) to "f" <logger name="*" minlevel="Debug" writeTo="f" /> --> <logger name="*" writeTo="f,c" /> </rules> </nlog>NLog这个配置给我怎么加注释说明

在NLog配置文件中添加注释可以使用XML的注释标记`<!-- 注释内容 -->`，例如：

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"      
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      
      xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"      
      autoReload="true"      
      throwExceptions="false"      
      internalLogLevel="Off" 
      internalLogFile="c:\temp\nlog-internal.log">

    <!-- 定义变量 -->
    <variable name="myvar" value="myvalue"/>

    <!-- 定义日志输出目标 -->
    <targets>
        <!-- 文件日志 -->
        <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" 
                 archiveFileName="logs/archive.{#}.log" 
                 archiveEvery="Day" 
                 archiveNumbering="Rolling" 
                 maxArchiveFiles="30" 
                 concurrentWrites="true" 
                 keepFileOpen="false" encoding="utf-8">
            <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" >
                <column name="time" layout="${longdate:universalTime=false}" />
                <column name="threadid" layout="${threadid}"/>
                <column name="level" layout="${level:upperCase=true}"/>
                <column name="callsite" layout="${callsite:includeSourcePath=true}" />
                <column name="message" layout="${message}" />
                <column name="stacktrace" layout="${callsite:includeSourcePath=true}" />
                <column name="exception" layout="${exception:format=ToString}"/>
            </layout>
        </target>

        <!-- 控制台日志 -->
        <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" />
    </targets>

    <!-- 定义日志输出规则 -->
    <rules>
        <logger name="*" writeTo="f,c" />
    </rules>
</nlog>

在需要注释的地方添加注释即可，例如：

<!-- 定义变量 -->
<variable name="myvar" value="myvalue"/>

<!-- 定义日志输出目标 -->
<targets>
    <!-- 文件日志 -->
    <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" 
             archiveFileName="logs/archive.{#}.log" 
             archiveEvery="Day" 
             archiveNumbering="Rolling" 
             maxArchiveFiles="30" 
             concurrentWrites="true" 
             keepFileOpen="false" encoding="utf-8">
        <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" >
            <column name="time" layout="${longdate:universalTime=false}" />
            <column name="threadid" layout="${threadid}"/>
            <column name="level" layout="${level:upperCase=true}"/>
            <column name="callsite" layout="${callsite:includeSourcePath=true}" />
            <column name="message" layout="${message}" />
            <column name="stacktrace" layout="${callsite:includeSourcePath=true}" />
            <column name="exception" layout="${exception:format=ToString}"/>
        </layout>
    </target>

    <!-- 控制台日志 -->
    <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" />
</targets>

<!-- 定义日志输出规则 -->
<rules>
    <logger name="*" writeTo="f,c" />
</rules>