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Ruby on Rails: How do I add a not null constraint to an existing column using a migration?
In my Rails (3.2) app, I have a bunch of tables in my database but I forgot to add a few not null constraints. I've googled around but I can't find how to write a migration which adds not null to an existing column.
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What is the best way to count “find” results?
...ull lines :
$ time find -type f | wc -l
8
real 0m0.006s
user 0m0.003s
sys 0m0.000s
So my solution is faster =) (the important part is the real line)
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In mongoDb, how do you remove an array element by its index?
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138
There is no straight way of pulling/removing by array index. In fact, this is an open issue ht...
App Inventor 2 动态创建组件与布局教程 · App Inventor 2 中文网
... 推荐方案
三、Dynamic Components 扩展介绍
3.1 下载与导入
3.2 核心方法概览
3.3 支持的组件类型
四、基础操作：创建按钮和标签
4.1 动态创建一个按钮
4.2 动态创建标签和文本框
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iPhone UITextField - Change placeholder text color
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In AngularJS, what's the difference between ng-pristine and ng-dirty?
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edited May 23 '17 at 12:34
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answered Aug 6 '13 at 6:44
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Get selected subcommand with argparse
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answered Jan 1 '11 at 21:10
robertrobert
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How to implement if-else statement in XSLT?
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You have to reimplement it using <xsl:choose> tag:
<xsl:choose>
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Excel “External table is not in the expected format.”
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How to convert a LocalDate to an Instant?
...lDate requires a time-zone. Unlike some other date and time libraries, JSR-310 will not select the time-zone for you automatically, so you must provide it.
LocalDate date = LocalDate.now();
Instant instant = date.atStartOfDay(ZoneId.systemDefault()).toInstant();
This example uses the default time...