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How do I find which rpm package supplies a file I'm looking for?
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Furthermore, yum whatprovides ... only requires root if the application is a root package (i.e. it resides in /sbin). However, rpm -qf ... also requires root in order to read rpms from /sbin. Therefore, I propose that the root requirements are functionally equivalent for b...
MySQL ON DUPLICATE KEY UPDATE for multiple rows insert in single query
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INSERT INTO ... ON DUPLICATE KEY UPDATE will only work for MYSQL, not for SQL Server.
for SQL server, the way to work around this is to first declare a temp table, insert value to that temp table, and then use MERGE
Like this:
declare @Source table
(
name varchar(30),
age decimal(...
MySQL - How to select data by string length
Is there a MySQL function to do this (of course instead of string_length )?
6 Answers
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MySQL Select all columns from one table and some from another table
...mns from one table and just some columns from another table using JOIN? In MySQL.
4 Answers
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MySQL foreign key constraints, cascade delete
... When creating the tables, you need to specify InnoDB or another MySQL engine that's capable of CASCADE operations. Otherwise the MySQL default, MyISAM, will be used and MyISAM does not support CASCADE operations. To do this, just add ENGINE InnoDB before the last ;.
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Are there disadvantages to using a generic varchar(255) for all text-based fields?
...ould always store 255 characters.
But since you tagged this question with MySQL, I'll mention a MySQL-specific tip: as rows are copied from the storage engine layer to the SQL layer, VARCHAR fields are converted to CHAR to gain the advantage of working with fixed-width rows. So the strings in mem...
浅谈TCP优化 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...里就不一一说明了，有兴趣的读者可以自行查阅。
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如何调整「rwnd」到一个合理值
有很多人都遇到过网络传输速度过慢的问题，比如说明明是百兆网络，其最大传输数据的理论值怎么着也得有个十兆，但是实际情况却相距...
MQTT与TCP的区别 - 创客硬件开发 - 清泛IT社区，为创新赋能！
... Maori dictionary)。10. mqtt客户端connect时，可以带有用户名和密码，用于验证客户端。服务端可以根据clientid、IP地址、用户名等进行ACL访问控制。可以通过自定义应用消息实现客户端对服务端的身份验证。11. 有商业和开源的mqtt broke...
MySQL Results as comma separated list
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The intent is fine and MySQL will allow this, but be careful (generally) with your use of GROUP BY. The items in the select list need to be valid aggregates in the context of the GROUP BY clause. In this case, p.name is not strictly valid. Any d...
Linux C/C++程序常用的调试手段及异常排查总结 - C/C++ - 清泛网 - 专注C/C++及内核技术
...所有变量命名是否可以保持一致性？缩进，换行，可读性如何？
（驼峰、下划线，这个根据公司或者谷歌等的编码规范去做，至于缩进、换行、注释等，可以在经常使用的ide上安装相关格式化插件）
是否涉及动态资源
是...