大约有 6,000 项符合查询结果（耗时：0.0270秒） [XML]
Fastest check if row exists in PostgreSQL
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How about simply:
select 1 from tbl where userid = 123 limit 1;
where 123 is the userid of the batch that you're about to insert.
The above query will return either an empty set or a single row, depending on whether there are records with the given userid.
If this turns o...
Installing PG gem on OS X - failure to build native extension
...any others have had problems installing the pg gem. None of the solutions posed for others have worked for me.
15 Answers
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How do I run Asynchronous callbacks in Playground
...swered Nov 25 '16 at 10:58
bradd123bradd123
9111 silver badge22 bronze badges
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Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
...he tendency to generate noticeably faster code if I optimize for size ( -Os ) instead of speed ( -O2 or -O3 ), and I have been wondering ever since why.
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Insert all values of a table into another table in SQL
...dited Feb 26 '14 at 1:12
hichris123
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answered Apr 21 '10 at 9:35
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If statement in aspx page
...erver">
<% If Request.QueryString("id_query_param") = 123 Then 'Add some VB comment here,
'which will not be visible in the rendered source code of the aspx page later %>
<!-- add some html content depending on -->
<!-- the conditi...
How do I check OS with a preprocessor directive?
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The Predefined Macros for OS site has a very complete list of checks. Here are a few of them, with links to where they're found:
Windows
_WIN32 Both 32 bit and 64 bit
_WIN64 64 bit only
Unix (Linux, *BSD, Mac OS X)
See this relate...
How do I fetch a single model in Backbone?
...ers with the hashbang in your URL like so, http://www.mydomain.com/#clocks/123 , but it should work even if you haven't yet.
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Find full path of the Python interpreter?
...will return the correct full binary path via sys.executable. Perhaps your OS or Python version behaves slightly differently.
– kevinarpe
May 22 '15 at 12:56
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Correct approach to global logging in Golang
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Create a single log.Logger and pass it around?
That is possible. A log.Logger can be used concurrently from multiple goroutines.
Pass around a pointer to that log.Logger?
log.New returns a *Logger which is usually an indication that you should pass the object around as...