大约有 48,000 项符合查询结果（耗时：0.0694秒） [XML]
What does it mean by select 1 from table?
...not to).
EDIT
There actually is one case which I forgot about until just now. In the case where you are trying to determine existence of a value in the database from an outside language, sometimes SELECT 1 FROM TABLE_NAME will be used. This does not offer significant benefit over selecting an indi...
How do I check in SQLite whether a table exists?
... query a table that possibly doesn't exist? This is the problem I'm facing now, and the accepted answer works best in this general problem statement. This is a good quick alternative.
– Dagrooms
Jun 16 '15 at 18:15
...
MySQL - force not to use cache for testing speed of query
...rrent date/time will disable the query cache for that selection:
SELECT *,NOW() FROM TABLE
See "Prerequisites and Notes for MySQL Query Cache Use" @ http://dev.mysql.com/tech-resources/articles/mysql-query-cache.html
shar...
Is there a “do … until” in Python? [duplicate]
...ce/generator that does not satisfy the predicate function - that's how it knows to stop taking. But if you then want to iterate over the rest thinking "now I'll get everything where the predicate was False", you'll miss the first item of those.
– PaulMcG
Jul 18...
CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true
...
Ah, now that's more convenient, however, the result's the same :( BTW, I'm using app.use(cors({credentials: true}));
– ixaxaar
Nov 2 '13 at 15:34
...
Go to back directory browsing after opening file in vim
...
@veich Thanks for your comment, but I won't do that for now since the question is only about going backward. This is not a wiki page, I'm just summarizing the other questions for the sake of clarity. Hope you understand that.
– ezdazuzena
Jun...
Check if image exists on server using JavaScript?
...request.
$.get(image_url)
.done(function() {
// Do something now you know the image exists.
}).fail(function() {
// Image doesn't exist - do something else.
})
share
|
...
How do I get the key at a specific index from a Dictionary in Swift?
...
@Max, this is old Swift syntax. Now you can use: dict.enumerated().forEach { (index, element) in ... }
– Matthew Korporaal
Jan 15 '19 at 10:28
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submit a form in a new tab
... my english is so crap. I edited the topic, hope is more comprensive right now :)
– markzzz
Apr 18 '11 at 22:26
...
What's the difference between a continuation and a callback?
..., 4));
function pythagoras(x, y) {
return x * x + y * y;
}
Now if every operation (including addition, multiplication, etc.) were written in the form of functions then we would have:
console.log(pythagoras(3, 4));
function pythagoras(x, y) {
return add(square(x), square(...