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When and why are database joins expensive?
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Denormalising to improve performance? It sounds convincing, but it doesn't hold water.
Chris Date, who in company with Dr Ted Codd was the original proponent of the relational data model, ran out of patience with misinformed arguments against normalisation and systematically demolished them...
Javascript foreach loop on associative array object
...cause in that code you're not using it like a JavaScript array. JavaScript does not have "associative arrays" like some other languages.
– Pointy
Sep 14 '13 at 17:51
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Why don't structs support inheritance?
...values inline, then we have a problem.
We have a problem because Square() doesn't know anything about Derived, it'll use only pointer arithmetic to access each element of the array, incrementing by a constant amount (sizeof(A)). The assembly would be vaguely like:
for (int i = 0; i < values.Le...
Test if element is present using Selenium WebDriver?
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This will return true if at least one element is found and false if it does not exist.
The official documentation recommends this method:
findElement should not be used to look for non-present elements, use findElements(By) and assert zero length response instead.
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Overloading member access operators ->, .*
...d it, you can take any arguments you like and return anything you want. It doesn't even have to be a nonstatic member.
In other words, this one is just a normal binary operator like +, -, and /. See also: Are free operator->* overloads evil?
.* and .
These cannot be overloaded. There is alread...
How to set Sqlite3 to be case insensitive when string comparing?
...that tripped me up: select * from tbl where firstname='john' and lastname='doe' COLLATE NOCASE will be case insensitive on lastname. To be case insensitive on firstname, write this: select * from tbl where firstname='john' COLLATE NOCASE and lastname='doe'. It's specific to that one column, not the ...
How can a web application send push notifications to iOS devices? [closed]
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Thanks for this answer, I was looking for the same. Does this also apply when you have added a meta tag 'apple-mobile-web-app-capable'?
– Mark Knol
Nov 28 '12 at 8:17
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Importing CSV with line breaks in Excel 2007
...data from csv-file (open in Editor), then perform "text in columns" --> does not work, all right.
Go to the next tab and copy/paste again (same thing what you have got already in your clipboard) --> automagically works now.
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“Comparison method violates its general contract!”
Can someone explain me in simple terms, why does this code throw an exception, "Comparison method violates its general contract!", and how do I fix it?
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Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?
...xes can be used to enforce restraints on data, because the database system does not allow the distinct values rule to be broken when inserting or updating data.
Your database system may allow a UNIQUE index to be applied to columns which allow NULL values, in which case two rows are allowed to be id...