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INNER JOIN vs LEFT JOIN performance in SQL Server

... slower; by definition, an outer join (LEFT JOIN or RIGHT JOIN) has to do all the work of an INNER JOIN plus the extra work of null-extending the results. It would also be expected to return more rows, further increasing the total execution time simply due to the larger size of the result set. (A...
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What do two question marks together mean in C#?

...e following statement will assign the first non-null Answer# to Answer (if all Answers are null then the Answer is null): string Answer = Answer1 ?? Answer2 ?? Answer3 ?? Answer4; Also it's worth mentioning while the expansion above is conceptually equivalent, the result of each expression is o...
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What is the purpose of the '@' symbol in CSS?

...ructs. The @ syntax itself, though, as I mentioned, is not new. These are all known in CSS as at-rules. They're special instructions for the browser, not directly related to styling of (X)HTML/XML elements in Web documents using rules and properties, although they do play important roles in control...
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How to show the last queries executed on MySQL?

Is there any query/way to show the last queries executed on ALL servers? 10 Answers ...
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Is it possible to read the value of a annotation in java?

...ation and if the annotation policy retains the annotation at runtime. Naturally if the retention policy doesn't keep the annotation at runtime, you won't be able to query it at runtime. An answer that's since been deleted (?) provided a useful link to an annotations tutorial that you may find helpf...
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How to drop a list of rows from Pandas dataframe?

... this doesnt allow you to index on the index name itself – ingrid Nov 2 '16 at 20:33 47 ...
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“Find next” in Vim

...for example, ?cake) instead of /, it is the other way round. If it is installed on your system, you should try to run vimtutor command from your terminal, which will start a tutorial of the basic Vim commands. Rob Wells advice about * and # is also very pertinent. ...
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How to measure time taken by a function to execute

...ction you're measuring time for var t1 = performance.now() console.log("Call to doSomething took " + (t1 - t0) + " milliseconds.") NodeJs: it is required to import the performance class Using console.time: (non-standard) (living standard) console.time('someFunction') someFunction() // W...
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A simple scenario using wait() and notify() in java

...imple scenario i.e. tutorial that suggest how this should be used, specifically with a Queue? 6 Answers ...
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How do I uninstall a package installed using npm link?

When installing a node package using sudo npm link in the package's directory, how can I uninstall the package once I'm done with development? ...