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If table exists drop table then create it, if it does not exist just create it

...s case than not to cover, see locking note below). Second RENAME ... atomically replaces table definition, refer to MySQL manual for details. At last, DROP ... just cleans up the old table, obviously. Wrapping all statements with something like SELECT GET_LOCK('__upgrade', -1); ... DO RELEASE_LOCK...
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What does the Q_OBJECT macro do? Why do all Qt objects need this macro?

I just started using Qt and noticed that all the example class definitions have the macro Q_OBJECT as the first line. What is the purpose of this preprocessor macro? ...
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How to search a specific value in all tables (PostgreSQL)?

... at 11:55 Mike Sherrill 'Cat Recall'Mike Sherrill 'Cat Recall' 78.5k1616 gold badges103103 silver badges156156 bronze badges ...
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How to make a class JSON serializable

...t;>> magic(f) '{"fname": "/foo/bar"}' In that case you can merely call json.dumps(f.__dict__). If you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization. For a trivial example, see below. >>> from json import JSONE...
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Add a new column to existing table in a migration

... }); } Then you can run your migrations: php artisan migrate This is all well covered in the documentation for both Laravel 3: Schema Builder Migrations And for Laravel 4 / Laravel 5: Schema Builder Migrations Edit: use $table->integer('paid')->after('whichever_column'); to add ...
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Is it possible to run a single test in MiniTest?

I can run all tests in a single file with: 13 Answers 13 ...
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Static files in Flask - robot.txt, sitemap.xml (mod_wsgi)

... achieved.) it's not clean to add static files into the app root folder finally, the proposed solution looks much cleaner than the adding middleware approach: share | improve this answer |...
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Check if a class has a member function of a given signature

...oid ReportMemUsage(const TMap& m, std::true_type) { // We may call used_memory() on m here. } template<typename TMap> void ReportMemUsage(const TMap&, std::false_type) { } template<typename TMap> void ReportMemUsage(const TMap& m) { ReportMemUsage(m, std:...
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How can I use UUIDs in SQLAlchemy?

... dialect supports UUID columns. This is easy (and the question is specifically postgres) -- I don't understand why the other answers are all so complicated. Here is an example: from sqlalchemy.dialects.postgresql import UUID from flask_sqlalchemy import SQLAlchemy import uuid db = SQLAlchemy() ...
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Regular Expression for alphanumeric and underscores

...o or more of the given characters $ : end of string If you don't want to allow empty strings, use + instead of *. As others have pointed out, some regex languages have a shorthand form for [a-zA-Z0-9_]. In the .NET regex language, you can turn on ECMAScript behavior and use \w as a shorthand (y...