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How to access random item in list?
... isn't repeated? Let's say I wanted to shuffle a deck of cards by randomly selecting one at a time, but obviously can't select the same card twice.
– AdamMc331
Sep 21 '14 at 5:26
7...
#1071 - Specified key was too long; max key length is 1000 bytes
... the best prefix length for a given column? Here's a method to find out:
SELECT
ROUND(SUM(LENGTH(`menu_link`)<10)*100/COUNT(`menu_link`),2) AS pct_length_10,
ROUND(SUM(LENGTH(`menu_link`)<20)*100/COUNT(`menu_link`),2) AS pct_length_20,
ROUND(SUM(LENGTH(`menu_link`)<50)*100/COUNT(`menu_...
How to create a video from images with FFmpeg?
...
-pattern_type glob
This great option makes it easier to select the images in many cases.
Slideshow video with one image per second
ffmpeg -framerate 1 -pattern_type glob -i '*.png' \
-c:v libx264 -r 30 -pix_fmt yuv420p out.mp4
Add some music to it, cutoff when the presumably...
Aggregate / summarize multiple variables per group (e.g. sum, mean)
...-date), sum)
# summarising a specific set of non-grouping variables using select_helpers
# see ?select_helpers for more options
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(starts_with('x')), sum)
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(matches('.*...
Timer function to provide time in nano seconds using C++
... result in these routines returning
different values as the thread moves from one processor to another...
However this StackOverflow answer https://stackoverflow.com/a/4588605/34329 states that QPC should work fine on any MS OS after Win XP service pack 2.
This article shows that Windows 7 can ...
How to use enum values in f:selectItem(s)
I want to make a selectOneMenu dropdown so I can select a status on my question. Is it possible to make the f:selectItem more flexible considering what happens if the order of the enums changes, and if the list was large? And could I do this better? And is it possible to automatically "select" the i...
What's the difference between a catalog and a schema in a relational database?
...
From the relational point of view :
The catalog is the place where--among other things--all of the various schemas (external, conceptual, internal) and all of the corresponding mappings (external/conceptual, conceptual/i...
Validation of radio button group using jQuery validation plugin
...to perform validation for a radio button group (one radio button should be selected) using jQuery validation plugin?
8 Answ...
HQL ERROR: Path expected for join
...
select u from UserGroup ug inner join ug.user u
where ug.group_id = :groupId
order by u.lastname
As a named query:
@NamedQuery(
name = "User.findByGroupId",
query =
"SELECT u FROM UserGroup ug " +
"INNER JOIN...
Why doesn't await on Task.WhenAll throw an AggregateException?
...
Excellent clear answer, this should IMO be the selected one.
– bytedev
Feb 22 '18 at 17:16
3
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