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JPA EntityManager: Why use persist() over merge()?
EntityManager.merge() can insert new objects and update existing ones.
15 Answers
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Long-held, incorrect programming assumptions [closed]
I am doing some research into common errors and poor assumptions made by junior (and perhaps senior) software engineers.
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INSERT INTO vs SELECT INTO
...To address your edit, they do different things. If you are making a table and want to define the structure use CREATE TABLE and INSERT. Example of an issue that can be created: You have a small table with a varchar field. The largest string in your table now is 12 bytes. Your real data set will ...
Difference between map, applymap and apply methods in Pandas
...rame’s apply method does exactly this:
In [116]: frame = DataFrame(np.random.randn(4, 3), columns=list('bde'), index=['Utah', 'Ohio', 'Texas', 'Oregon'])
In [117]: frame
Out[117]:
b d e
Utah -0.029638 1.081563 1.280300
Ohio 0.647747 0.831136 -1.549481
Tex...
Pushing an existing Git repository to SVN
I've been doing all my work in Git and pushing to GitHub. I've been very happy with both the software and the site, and I have no wish to change my working practices at this point.
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Remove duplicate rows in MySQL
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The aforementioned bug @DarkMantis referred to and it's solution.
– Jordan Arseno
Jan 23 '13 at 20:47
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RegEx for matching UK Postcodes
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I'd recommend taking a look at the UK Government Data Standard for postcodes [link now dead; archive of XML, see Wikipedia for discussion]. There is a brief description about the data and the attached xml schema provides a regular expression. It may not be exactly what you want bu...
Add an already existing directory to a directory in Solution Explorer
...irectory in Solution Explorer, but whenever I right-click on the directory and select Add => Existing Item , I can only add individual files, but not directories.
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One class per file rule in .NET? [closed]
I follow this rule but some of my colleagues disagree with it and argue that if a class is smaller it can be left in the same file with other class(es).
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Interface vs Abstract Class (general OO)
...nterviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I don't know what it is.
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