<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[j573749的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/j573749</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; j573749]]></copyright><item><title><![CDATA[MYSQL 事务-1]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155716953</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155716953</guid><author>j573749</author><pubDate>Mon, 08 Dec 2025 23:43:41 +0800</pubDate><description><![CDATA[事务]]></description><category></category></item><item><title><![CDATA[MYSQL-索引]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155613774</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155613774</guid><author>j573749</author><pubDate>Fri, 05 Dec 2025 20:29:09 +0800</pubDate><description><![CDATA[mysql 索引机制]]></description><category></category></item><item><title><![CDATA[MYSQL 表的內连与外连]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155359797</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155359797</guid><author>j573749</author><pubDate>Fri, 28 Nov 2025 18:32:53 +0800</pubDate><description><![CDATA[mysql  内外连接]]></description><category></category></item><item><title><![CDATA[MYSQL 复合查询]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155321616</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155321616</guid><author>j573749</author><pubDate>Thu, 27 Nov 2025 22:49:36 +0800</pubDate><description><![CDATA[mysql复合查询 自链接 多表查询 多列子查询 单列子查询]]></description><category></category></item><item><title><![CDATA[MYSQL 内置函数]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155271454</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155271454</guid><author>j573749</author><pubDate>Wed, 26 Nov 2025 16:12:48 +0800</pubDate><description><![CDATA[mysql 内置函数 ]]></description><category></category></item><item><title><![CDATA[MYSQL 表的增删查改-更新/删除]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155194211</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155194211</guid><author>j573749</author><pubDate>Mon, 24 Nov 2025 19:08:00 +0800</pubDate><description><![CDATA[这里是使用的having关键字，其用作与where的作用一样，都是按列进行筛选，但是优先序不同，where的优先序很高，仅在from table_name的后面，having的优先序在这里是最低的，所以是可以表数据进行分组，聚合，重命名，最后再根据having的表达式进行筛选数据。指定修改的表和列，使用where，order by limit等关键字筛选出具体需要修改的数据，通过set修改。只能对整表操作，实际上mysql不对数据做任何操作，并不走事务的流程，效率比delete更快，也无法回滚。]]></description><category></category></item><item><title><![CDATA[MYSQL 表的增删查改-Retrieve]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155109981</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155109981</guid><author>j573749</author><pubDate>Fri, 21 Nov 2025 21:50:33 +0800</pubDate><description><![CDATA[mysql 表 查找 retrieve]]></description><category></category></item><item><title><![CDATA[MYSQL 数据类型-2]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155107381</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155107381</guid><author>j573749</author><pubDate>Fri, 21 Nov 2025 19:00:52 +0800</pubDate><description><![CDATA[varchar还是一个可边长字符串，意思是，char呢我们设置了char(5)，那么每一个数据都是存放在一个3*5字节的空间中的，可能我们在这一行中只对其插入了1个或2，3，4个字符，但是其需要的空间都是相同的15字节。varchar(5)就不一样，若我们只输入1个字符的空间就会为其创建一个字符的空间3字节，不会为其创建一个15字节的空间，这是通过一个标记值实现的，无论varchar我们设置多少个字符位，都要有一个字符位置-3字节用于存放当前字符串的位数。所以3=0011就是1，2选项。]]></description><category></category></item><item><title><![CDATA[Linux 进程间通信-1]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155099264</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155099264</guid><author>j573749</author><pubDate>Fri, 21 Nov 2025 13:58:21 +0800</pubDate><description><![CDATA[管道介绍 命名管道]]></description><category></category></item><item><title><![CDATA[MYSQL表的增删查改-增]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155076316</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155076316</guid><author>j573749</author><pubDate>Thu, 20 Nov 2025 22:01:39 +0800</pubDate><description><![CDATA[mysql 表新增数据]]></description><category></category></item><item><title><![CDATA[MySQL表的约束 -2]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155065643</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155065643</guid><author>j573749</author><pubDate>Thu, 20 Nov 2025 16:15:38 +0800</pubDate><description><![CDATA[表约束 自增 唯一键 外键]]></description><category></category></item><item><title><![CDATA[Linux基础IO-2]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155015698</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155015698</guid><author>j573749</author><pubDate>Wed, 19 Nov 2025 15:16:40 +0800</pubDate><description><![CDATA[linux 文件系统 动静态库 ]]></description><category></category></item><item><title><![CDATA[MYSQL表的约束-1]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/155000303</link><guid>https://blog.youkuaiyun.com/j573749/article/details/155000303</guid><author>j573749</author><pubDate>Tue, 18 Nov 2025 21:17:31 +0800</pubDate><description><![CDATA[表的约束  空属性 默认值 列描述 0填充 主键]]></description><category></category></item><item><title><![CDATA[Linux： 基础IO介绍 -2]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/154987378</link><guid>https://blog.youkuaiyun.com/j573749/article/details/154987378</guid><author>j573749</author><pubDate>Tue, 18 Nov 2025 14:00:49 +0800</pubDate><description><![CDATA[fd表里面是一个个的指针，每个指针指向一个struct file{}结构体，如图结构体里包含很多的属性，其里面有一个inode的指针，indeo也是一个结构体，但是操作系统会为其创建一个内存缓冲，indeo里面包含了对磁盘文件的索引，当我们访问某一个文件时，进程通过inode索引将文件数据读取到缓冲区中。分别对应文件描述符表下标0，1，2，继续打开文件就会从3开始一直向后占用数组，当我们关闭了某一文件，如1号下标对应的文件，当我们再打开一个文件时就会占用1号小标的数组空间。，这就是文件描述符表。]]></description><category></category></item><item><title><![CDATA[MYSQL数据类型-1]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/154959219</link><guid>https://blog.youkuaiyun.com/j573749/article/details/154959219</guid><author>j573749</author><pubDate>Mon, 17 Nov 2025 22:02:25 +0800</pubDate><description><![CDATA[mysql数据类型 bit int tinyint mallint bigint float decimal double]]></description><category></category></item><item><title><![CDATA[Linux：基础IO介绍-1]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/154563016</link><guid>https://blog.youkuaiyun.com/j573749/article/details/154563016</guid><author>j573749</author><pubDate>Mon, 17 Nov 2025 12:24:51 +0800</pubDate><description><![CDATA[基础IO  fopen  open函数]]></description><category></category></item><item><title><![CDATA[MYSQL结构操作DDL指令2.表操作]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/154846856</link><guid>https://blog.youkuaiyun.com/j573749/article/details/154846856</guid><author>j573749</author><pubDate>Fri, 14 Nov 2025 20:39:09 +0800</pubDate><description><![CDATA[表结构操作 ]]></description><category></category></item><item><title><![CDATA[MYSQL结构操作DDL指令1.数据库操作]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/154842560</link><guid>https://blog.youkuaiyun.com/j573749/article/details/154842560</guid><author>j573749</author><pubDate>Fri, 14 Nov 2025 18:47:22 +0800</pubDate><description><![CDATA[DDL操作 数据库 ]]></description><category></category></item><item><title><![CDATA[定长内存池]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/143967469</link><guid>https://blog.youkuaiyun.com/j573749/article/details/143967469</guid><author>j573749</author><pubDate>Fri, 22 Nov 2024 11:44:16 +0800</pubDate><description><![CDATA[定长内存池]]></description><category></category></item><item><title><![CDATA[C++ list容器]]></title><link>https://blog.youkuaiyun.com/j573749/article/details/143869453</link><guid>https://blog.youkuaiyun.com/j573749/article/details/143869453</guid><author>j573749</author><pubDate>Mon, 18 Nov 2024 23:59:15 +0800</pubDate><description><![CDATA[C++容器list  模拟实现STL中的list的功能  ]]></description><category></category></item></channel></rss>