Machine Learning Done WrongStatistical modeling is a lot like engineering.In engineering, there are various ways to build a key-value storage, and eac...
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系统相关 时间:
2015-07-26 15:28:52
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126
Amr has got a large array of sizen. Amr doesn't like large arrays so he intends to make it smaller.Amr doesn't care about anything in the array except...
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其他好文 时间:
2015-07-26 00:23:03
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133
SHOW CHARACTER SET显示所有可用的字符集SHOW CHARACTER SET;SHOW CHARACTER SET LIKE 'latin%';SHOW COLLATION输出包括所有可用的字符集SHOW COLLATION;SHOW COLLATION LIKE 'latin1%'...
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数据库 时间:
2015-07-25 22:54:56
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273
出处:http://xiahouzuoxin.github.io/notesKalman滤波器的历史渊源We are like dwarfs on the shoulders of giants, by whose grace we see farther than they. Our study ...
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其他好文 时间:
2015-07-25 13:36:14
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799
B. LunchTime Limit: 20 SecMemory Limit: 256 MB题目连接http://codeforces.com/gym/100637/problem/BDescriptionThe swamp looks like a narrow lane with length ...
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其他好文 时间:
2015-07-24 20:21:41
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223
Jenkins has many plugins to communicate with source code management server. Like CVS, git, perforce etc. My company uses P4 as our source code reposit...
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其他好文 时间:
2015-07-24 17:43:17
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136
Immutable dictionaries can be defined using the literal @{} syntax. But, like array literals, this was added relatively recently, so you should also b...
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其他好文 时间:
2015-07-23 19:43:03
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98
给出一个字符串@"I am a boy,I like playing computer games",然后我们尽我们所能的调戏它. NSString *string=@"I am a boy,I like playing computer games"; NSMutableString*mS...
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其他好文 时间:
2015-07-23 06:54:52
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127
一、变量的定义与赋值declare @变量名 类型set @变量名=值eg、 查汽车表中名称含有宝马两个字的declare @name varchar(20)set @name='宝马'select * from car where Name like '%'+@name+'%' 查汽车表中所有汽车...
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数据库 时间:
2015-07-23 00:13:16
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177
1、使用索引查询记录时,一定要注意索引的使用情况,例如:
(1)like关键字配置的字符串不能以‘%’开头
(2)使用多列索引时,查询条件必须要使用这个索引的第一个字段
(3)使用or关键字时,or关键字连接的所有条件都必须使用索引
2.优化子查询
很多查询中需要使用子查询,但子查询执行效率不高,子查询时,mysql需要为内层查询语句的查询结果建立一个临时表,然后外层查询语句再在...
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数据库 时间:
2015-07-22 22:41:58
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181