大约有 47,000 项符合查询结果（耗时：0.0635秒） [XML]
how to exclude null values in array_agg like in string_agg using postgres?
... non_canonical_users
FROM groups g
GROUP BY g.id
) s
Or, simpler and may be cheaper, using array_to_string which eliminates nulls:
SELECT
g.id,
array_to_string(
array_agg(CASE WHEN g.canonical = 'Y' THEN g.users ELSE NULL END)
, ','
) canonical_users,
array...
Why are Subjects not recommended in .NET Reactive Extensions?
...currently getting to grips with the Reactive Extensions framework for .NET and I am working my way through the various introduction resources I've found (mainly http://www.introtorx.com )
...
Android: install .apk programmatically [duplicate]
I made this with help from
Android download binary file problems
and Install Application programmatically on Android .
...
Error: could not find function … in R
I am using R and tried some.function but I got following error message:
10 Answers
1...
Change Active Menu Item on Page Scroll?
...
If your menu has a mix of on-page IDs and regular pages, place the on-page ID links first, then change menuItems = topMenu.find("a"), to menuItems = topMenu.find("a").slice(0,4),, replacing 4 with [your on-page links - 1].
– Stephen Saucier
...
Why is it faster to check if dictionary contains the key, rather than catch the exception in case it
...
On the one hand, throwing exceptions is inherently expensive, because the stack has to be unwound etc.
On the other hand, accessing a value in a dictionary by its key is cheap, because it's a fast, O(1) operation.
BTW: The correct way t...
iPhone Simulator location
...
As of Xcode 6 and iOS 8 you’ll find it here:
~/Library/Developer/CoreSimulator/Devices/{cryptic number}/data/Containers/Data/Application/{cryptic number}/
or you can get it from below code execution:
NSLog(@"Documents Directory: %@"...
How to timeout a thread
...eted within that time, I want to either kill it, throw some exception, or handle it in some way. How can it be done?
17 Ans...
Highlight all occurrence of a selected word?
...
In Normal mode:
:set hlsearch
Then search for a pattern with the command / in Normal mode, or <Ctrl>o followed by / in Insert mode. * in Normal mode will search for the next occurrence of the word under the cursor. The hlsearch option will highlight all of them if set. # will search for ...
How to solve “Fatal error: Class 'MySQLi' not found”?
I am doing a tutorial and am getting this error:
22 Answers
22
...