大约有 40,000 项符合查询结果（耗时：0.0357秒） [XML]
Select rows which are not present in other table
...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
);
Also consider:
What is easier to read in EXISTS...
How to see which flags -march=native will activate?
I'm compiling my C++ app using GCC 4.3. Instead of manually selecting the optimization flags I'm using -march=native , which in theory should add all optimization flags applicable to the hardware I'm compiling on. But how can I check which flags is it actually using?
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Summarizing multiple columns with dplyr? [duplicate]
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I mean, the behavior like in select would be great: summarize(df, a:c, d=paste(d, collaspe =',' ) . Just want to put more original columns in for reference
– biocyberman
Aug 8 '15 at 17:28
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Capture Image from Camera and Display in Activity
...f I don't like the image I can delete it and click one more image and then select the image and it should return back and display that image in the activity.
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Traits in PHP – any real world examples/best practices? [closed]
... solve this nicely by allowing me to keep the boilerplate in one place and selectively apply it where needed.
Note: given that traits are a new concept in PHP, all opinion expressed above is subject to change. I've not have had much time to evaluate the concept myself yet. But I hope it is good eno...
How to convert a color integer to a hex String in Android?
...sure you only get RRGGBB, and the %06X gives you zero-padded hex (always 6 chars long):
String hexColor = String.format("#%06X", (0xFFFFFF & intColor));
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How to get all options of a select using jQuery?
How can I get all the options of a select through jQuery by passing on its ID?
17 Answers
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React JSX: selecting “selected” on selected option
In a React component for a <select> menu, I need to set the selected attribute on the option that reflects the application state.
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Sublime - delete all lines containing specific value
...e got stuck for several minutes when I did Ctrl+Shift+K with 200,000 lines selected.
– Przemek D
Aug 28 '17 at 11:43
I...
How to set timeout on python's socket recv method?
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The typical approach is to use select() to wait until data is available or until the timeout occurs. Only call recv() when data is actually available. To be safe, we also set the socket to non-blocking mode to guarantee that recv() will never block indef...