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How to rollback a specific migration?
...1
Is a way to do this, if the migration you want to rollback is the last one applied. You can substitute 1 for however many migrations you want to go back.
For example:
rake db:rollback STEP=5
Will also rollback all the migration that happened later (4, 3, 2 and also 1).
To roll back all migr...
Hash String via SHA-256 in Java
...out more information it would be hard to say why you are getting different ones. You should probably open a new question.
– Brendan Long
Aug 9 '10 at 21:16
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How can I prevent SQL injection in PHP?
... Also, the official documentation of mysql_query only allows to execute one query, so any other query besides ; is ignored. Even if this is already deprecated there are a lot of systems under PHP 5.5.0 and that may use this function. php.net/manual/en/function.mysql-query.php
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COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...bleHere.*), use that.
In short, don't use COUNT(1) for anything. It's a one-trick pony, which rarely does what you want, and in those rare cases is equivalent to count(*)
Use count(*) for counting
Use * for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_...
“Default Activity Not Found” on Android Studio upgrade
...ity, to be launched when the application starts.
You should have at least one activity that looks something like this:
<activity
android:name="com.your.package.name.YourActivity"
android:label="@string/app_name">
<intent-filter>
<action android:na...
Can an input field have two labels?
...ach information to controls. Each LABEL element is associated with exactly one form control.
Thus, each form control can be referenced by multiple labels, but each label can only reference one control. So if it makes sense to have a second label for a control (and in the situation you describe, it...
Which UUID version to use?
...network card MAC address and a timer. These IDs are easy to predict (given one, I might be able to guess another one) and can be traced back to your network card. It's not recommended to create these.
Version 4: These are generated from random (or pseudo-random) numbers. If you just need to generate...
SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
I hope that made sense, let me elaborate:
10 Answers
10
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Applying .gitignore to committed files
...ere's a lot of files though. I don't want to have do this for every single one
– user880954
Sep 23 '11 at 11:08
1
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HTML 5: Is it , , or ?
... have your html be well-formed xml, that's it. Of course when transforming one into another you have to make sure it's still valid, but is it worth mentioning? :)
– Michael Krelin - hacker
Dec 22 '09 at 14:37
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