大约有 48,000 项符合查询结果（耗时：0.0724秒） [XML]
Select rows which are not present in other table
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There are basically 4 techniques for this task, all of them standard SQL.
NOT EXISTS
Often fastest in Postgres.
SELECT ip
FROM login_log l
WHERE NOT EXISTS (
SELECT -- SELECT list mostly irrelevant; can just be empty in Postgres
FROM ip_location
WHERE ip = l.ip
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jQuery/JavaScript to replace broken images
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Handle the onError event for the image to reassign its source using JavaScript:
function imgError(image) {
image.onerror = "";
image.src = "/images/noimage.gif";
return true;
}
<img src="image.png" onerror=...
Why is it bad style to `rescue Exception => e` in Ruby?
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TL;DR: Use StandardError instead for general exception catching. When the original exception is re-raised (e.g. when rescuing to log the exception only), rescuing Exception is probably okay.
Exception is the root of Ruby's exception hi...
Javascript foreach loop on associative array object
...ow to note that the Object.keys() function is available on modern browsers and in Node etc. That function returns the "own" keys of an object, as an array:
Object.keys(arr_jq_TabContents).forEach(function(key, index) {
console.log(this[key]);
}, arr_jq_TabContents);
The callback function passed...
How to search for occurrences of more than one space between words in a line
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[ ]{2,}
SPACE (2 or more)
You could also check that before and after those spaces words follow. (not other whitespace like tabs or new lines)
\w[ ]{2,}\w
the same, but you can also pick (capture) only the spaces for tasks like replacement
\w([ ]{2,})\w
or see that before and af...
How to view files in binary from bash?
...he contents of a file in the current directory, but in binary from the command line. How can I achieve this?
11 Answers
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How to check if std::map contains a key without doing insert?
The only way I have found to check for duplicates is by inserting and checking the std::pair.second for false , but the problem is that this still inserts something if the key is unused, whereas what I want is a map.contains(key); function.
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How to find encoding of a file via script on Linux?
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Sounds like you're looking for enca. It can guess and even convert between encodings. Just look at the man page.
Or, failing that, use file -i (linux) or file -I (osx). That will output MIME-type information for the file, which will also include the character-set encoding. ...
How does Python's super() work with multiple inheritance?
I'm pretty much new in Python object oriented programming and I have trouble
understanding the super() function (new style classes) especially when it comes to multiple inheritance.
...
Passing current scope to an AngularJS Service
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@Caio Cunha Could you expand on why it's not a good idea to pass a scope? I'm having exactly this issue, I want to add some stuff to $scope via a call to a service using an async executeSql() function. Looking into 3 options (1) use a callback on the...