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Fastest way to determine if an integer's square root is an integer
...st way to determine if a long value is a perfect square (i.e. its square root is another integer):
35 Answers
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How to avoid “Permission denied” when using pip with virtualenv
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Solution:
If you created the virtualenv as root, run the following command:
sudo chown -R your_username:your_username path/to/virtuaelenv/
This will probably fix your problem.
Cheers
share...
Rails 3: Get Random Record
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Thing.first(:order => "RANDOM()") # For MySQL :order => "RAND()", - thanx, @DanSingerman
# Rails 3
Thing.order("RANDOM()").first
or
Thing.first(:offset => rand(Thing.count))
# Rails 3
Thing.offset(rand(Thing.count)).first
Actually, in Rails 3 all example...
领域驱动设计系列（五）:事件驱动之异步事件 - 更多技术 - 清泛网 - 专注C/...
...以。
另外，异步要处理的东西很多，比如处理完毕后，如何通知用户，还是让用户刷新？ 我个人建议，一般情况下都不要用异步，只有在真的需要的时候再用。
作者: 王德水
出处：http://deshui.wang
领域驱动设计 DDD 事件驱...
Remove Primary Key in MySQL
... following table schema which maps user_customers to permissions on a live MySQL database:
12 Answers
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Generate GUID in MySQL for existing Data?
I've just imported a bunch of data to a MySQL table and I have a column "GUID" that I want to basically fill down all existing rows with new and unique random GUID's.
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When and why are database joins expensive?
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MySQL, Oracle, SQL Server, Sybase, postgreSQL,etc. care not the order of joins. I've worked with DB2 and it also, to my knowledge, doesn't care what order you put them in. This is not helpful advice in the general case
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how to convert a string to date in mysql?
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As was told at MySQL Using a string column with date text as a date field, you can do
SELECT STR_TO_DATE(yourdatefield, '%m/%d/%Y')
FROM yourtable
You can also handle these date strings in WHERE clauses. For example
SELECT whatever...
How to delete duplicates on a MySQL table?
I need to DELETE duplicated rows for specified sid on a MySQL table.
25 Answers
25...
【最全】CSS响应式布局的5种实现方式 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...整代码与文件 可进入粉丝群获取 ！
三、rem 布局
1、rem 如何适配
rem 是相对于 html 根元素的字体大小的单位。
我们通过修改 html 中 font-size 的字体大小来控制 rem 的大小。
比如：
html {
font-size: 10px;
}
.box {
width: 10rem;
...