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数据挖掘——分词入门 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...了解数据挖掘的目的：发现数据中价值。这个才是关键，如何发现数据中的价值。那什么是数据呢？比如大家要上网首先需要输入网址，打开网页后会自动判断哪些是图片、哪些是新闻、哪些是用户名称、游戏图标等。人大脑可...
PDO MySQL: Use PDO::ATTR_EMULATE_PREPARES or not?
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To answer your concerns:
MySQL >= 5.1.17 (or >= 5.1.21 for the PREPARE and EXECUTE statements) can use prepared statements in the query cache. So your version of MySQL+PHP can use prepared statements with the query cache. However, make careful ...
华为公司的新产品研发流程管理 - 项目管理 - 清泛网 - 专注C/C++及内核技术
...以企业的研发环节为例，技术纷繁复杂，更新变幻莫测，如何决策?如何投资?如何预算控制、...引言：高效率和高质量似乎永远是一对解不开的矛盾。以企业的研发环节为例，技术纷繁复杂，更新变幻莫测，如何决策?如何投资?...
SQL command to display history of queries
I would like to display my executed sql command history in my MYSQL Query Browser. What is the sql statement for displaying history?
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Update one MySQL table with values from another
I'm trying to update one MySQL table based on information from another.
2 Answers
2
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Gem::LoadError for mysql2 gem, but it's already in Gemfile
...upgrading to rails 4.2.4 (also with rails 4.1.5) try using this version of mysql2:
gem 'mysql2', '~> 0.3.18'
Apparently mysql2 isn't still compatible with newer version of rails because rails 4.2.4 is pretty new as the time of answering this question by me 8 September 2015 so use the above lin...
Is it possible to roll back CREATE TABLE and ALTER TABLE statements in major SQL databases?
...tive.
Is DDL transactional according to this document?
PostgreSQL - yes
MySQL - no; DDL causes an implicit commit
Oracle Database 11g Release 2 and above - by default, no, but an alternative called edition-based redefinition exists
Older versions of Oracle - no; DDL causes an implicit commit
SQL ...
Django MEDIA_URL and MEDIA_ROOT
...rest of your URLconf goes here ...
) + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
You no longer need if settings.DEBUG as Django will handle ensuring this is only used in Debug mode.
ORIGINAL answer for Django <= 1.6
Try putting this into your urls.py
from django.conf im...
MySQL Insert into multiple tables? (Database normalization?)
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No, you can't insert into multiple tables in one MySQL command. You can however use transactions.
BEGIN;
INSERT INTO users (username, password)
VALUES('test', 'test');
INSERT INTO profiles (userid, bio, homepage)
VALUES(LAST_INSERT_ID(),'Hello world!', 'http://www.sta...
Unicode与UTF-8互转(C语言实现) - C/C++ - 清泛网 - 专注C/C++及内核技术
...了符号的二进制代码, 却没有规定这
个二进制代码应该如何存储".
比如, 汉字"严"的unicode是十六进制数4E25, 转换成二进制数足足有15位
(100111000100101), 也就是说这个符号的表示至少需要2个字节. 表示其他更大的符号,
可能需要3...