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mysql - how many columns is too many?
...tables with many rows, modifying the indexes can take a very long time, as MySQL needs to rebuild all of the indexes in the table. Having the indexes split over several table could make that faster.
Depending on your queries and column types, MySQL could be writing temporary tables (used in more co...
MySQL - length() vs char_length()
...ore accurately UTF-16LE) is what Windows misleadingly calls “Unicode”. MySQL doesn't support UTF-16; instead the usual approach for putting Unicode strings in it is to use UTF-8.
– bobince
Nov 14 '09 at 14:20
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C++特化模板函数的符号多重定义错误问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
....h 中，结果出现特化模板函数的符号多重定义错误。我要如何组织头文件才能避免多重符号定义错误？我用 /FORCE:MULTIPLE，但我想用一个更好的解决方法。
Lee Kyung Jun
实际上，确实用更好的解决方法。稍后我会解释，但首先让我...
PDO closing connection
Just a rather simple question with regards to PDO compared to MySQLi.
5 Answers
5
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Unioning two tables with different number of columns
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无人驾驶汽车大难题 人工智能同人的差距显著 - 资讯 - 清泛网 - 专注C/C++...
...出，在谷歌总部所在的山景城进行公路测试，正式学习该如何与普通汽车在公路上共同行进。谷歌还事先在无人驾驶车的“大脑”里加入了山景城的高精度虚拟地图，但这显然很难复制。从这一点上看，互联网公司宣称的“无人...
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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File Hash 扩展：文件哈希计算和 Base64 编码文件，sha256、sha512 哈希 ·...
...全文件传输验证
备份文件一致性检查
文件去重比较
密码存储（建议使用加盐哈希）
相关功能
可以使用 Juan Antonio 的 Terminal 扩展 通过 Linux 命令获取文件的 SHA256 哈希：
sha256sum /absolute/path/to/file
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