## mysql – Getting only 4 rows per idea from ideas table

I have made one idea submission portal for diffrent ideas submitted by school students, as i am beginner in mega database management its really hard for me to write a query that retruns only 4 rows per idea and so on

for ex: for idea id DC889 > i need only 4 records but table contans 50 records. i tiried using having function or count function but not able to find out feasible soultion.

requesting expert guidance on the same so that i can apply my own login to write the query.

## Daisy chaining a lot of networking devices, is this a good idea?

I know a little about networking, but I wouldn’t even call myself a novice… so of course I am running CAT6a through my house. I would like to know if my plan makes any sense. I have a fiber modem that requires PPOE login and VLAN tagging 201, I already had a Google WiFi mesh network and some Netgear switches so I am trying to reuse as much as possible. But Google WiFi doesn’t support the VLAN tagging so I bought a stand alone wired router Ubiquiti ER4. My fiber modem is in a structured media center in my garage, I am planning on putting the router there along with a 8 port managed switch.

I was going to do a 10 foot run of two cables to a bedroom from the garage that would connect the router to the first WiFI AP and from that AP and have the AP’s network controlling everything in the house. The AP would plug into an 8 port unmanageable switch in that bedroom, and that switch would then plugin to the second run back down to the garage and into a basic “smart managed” switch. There is an 8 port patch panel in the garage where the garage switch will hook up all the runs in the house. I need the switch in the bedroom as well since I have 5 electronics that need hardwire connections.

I guess my main concern is it ok to have this daisy chain of equipment. Fiber modem -> Router -> Google WiFi mesh unit -> unmanaged switch -> managed switch -> Google WiFi mesh units / other electronics like PS4, etc… Should I reverse the switches? What if I have a third 5 port switch at the end?

## architecture – Is it a good idea to have separate instances for the public API Server and API Server used by the Web App?

I’ve built a React Web application with an Express REST API server and Firebase Auth. Also, Nginx is set up as a reverse proxy, so API calls from React to `https://mydomain.com/api` are routed to backend `http://localhost:8002`.

Now I want to publish part of my APIs under `https://api.mydomain.com` with an API Key scheme. I’ve modified the Express server so it can handle both auth schemes based on `Authorization` header (i.e. `Bearer` for Firebase, `ApiKey` for API Key).

The question is: Is it a good idea to have separate backends serving Web App and Public APIs? What benefits could it bring? Or should I direct API calls from the Web App to `api.mydomain.com` to keep setup simple?

## intellij idea – Erro de compilação do Maven: Falha ao executar o objetivo org.apache.maven.plugins: maven-compiler-plugin: 3.1: compilar no projeto Maven

estou tendo esse erro ao tentar executar a compilação Marvin

“C:Program FilesJavajdk1.8.0_111binjava.exe” -Dmaven.multiModuleProjectDirectory=C:UsersUserDocumentsglobalexemplo.marvenok “-Dmaven.home=C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1pluginsmavenlibmaven3” “-Dclassworlds.conf=C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1pluginsmavenlibmaven3binm2.conf” “-Dmaven.ext.class.path=C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1pluginsmavenlibmaven-event-listener.jar” “-javaagent:C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1libidea_rt.jar=60347:C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1bin” -Dfile.encoding=UTF-8 -classpath “C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1pluginsmavenlibmaven3bootplexus-classworlds-2.6.0.jar;C:Program FilesJetBrainsIntelliJ IDEA Community Edition 2020.3.1pluginsmavenlibmaven3bootplexus-classworlds.license” org.codehaus.classworlds.Launcher -Didea.version=2020.3.1 install
(INFO) Scanning for projects…
(INFO)
(INFO) ——————< br.com.globallabs:exemplo.marven >——————
(INFO) Building exemplo.marven 0.0.1-SNAPSHOT
(INFO) ——————————–( jar )———————————
(INFO)
(INFO) — maven-resources-plugin:3.2.0:resources (default-resources) @ exemplo.marven —
(INFO) Using ‘UTF-8’ encoding to copy filtered resources.
(INFO) Using ‘UTF-8’ encoding to copy filtered properties files.
(INFO) Copying 1 resource
(INFO) Copying 0 resource
(INFO)
(INFO) — maven-compiler-plugin:3.8.1:compile (default-compile) @ exemplo.marven —
(INFO) Changes detected – recompiling the module!
(INFO) Compiling 1 source file to C:UsersUserDocumentsglobalexemplo.marvenoktargetclasses
(INFO) ————————————————————————
(INFO) BUILD FAILURE
(INFO) ————————————————————————
(INFO) Total time: 2.888 s
(INFO) Finished at: 2021-01-17T12:49:37-03:00
(INFO) ————————————————————————
(ERROR) Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project exemplo.marven: Fatal error compiling: invalid target release: 11 -> (Help 1)
(ERROR)
(ERROR) To see the full stack trace of the errors, re-run Maven with the -e switch.
(ERROR) Re-run Maven using the -X switch to enable full debug logging.
(ERROR)
(ERROR) (Help 1) http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

Process finished with exit code 1

(INFO)
(INFO) ——————< br.com.globallabs:exemplo.marven >——————
(INFO) Building exemplo.marven 0.0.1-SNAPSHOT
(INFO) ——————————–( jar )———————————
(INFO)
(INFO) — maven-resources-plugin:3.2.0:resources (default-resources) @ exemplo.marven —
(INFO) Using ‘UTF-8’ encoding to copy filtered resources.
(INFO) Using ‘UTF-8’ encoding to copy filtered properties files.
(INFO) Copying 1 resource
(INFO) Copying 0 resource
(INFO)
(INFO) — maven-compiler-plugin:3.8.1:compile (default-compile) @ exemplo.marven —
(INFO) Changes detected – recompiling the module!
(INFO) Compiling 1 source file to C:UsersUserDocumentsglobalexemplo.marvenoktargetclasses

(INFO)
(INFO) — maven-compiler-plugin:3.8.1:compile (default-compile) @ exemplo.marven —
(INFO) Changes detected – recompiling the module!
(INFO) Compiling 1 source file to C:UsersUserDocumentsglobalexemplo.marvenoktargetclasses

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project exemplo.marven: Fatal error compiling

## Setting up Home Server for RDP Services – Good Idea or not | NewProxyLists

Hello WJ,

I am from Canada and I wanted to start an RDP service here.

For that, Instead of buying servers from outside, I decided to setup a server at my home and provide RDP services from there.

So far, I have setup a PC with 64GB DD4 RAM, Xeon E5-10600KF processor, 1 TB NVME SSD for the Operating System and 4TB additional Drive for the space for clients.

I wanted to ask you guys, what do you think is it a good way to proceed and will WJ like this ?

I have a Gigabit connection but unlike the ISP’s it;’s not going to be 900Mbps but after setup I will see what i get.

Post automatically merged:

I have to figure out the static IP i guess that’s one issue i have to resolve.

## In Blue Wallet 6.0.2 for iOS, pressing on Bump Fee causes an infinite wait. Any idea why?

Think there might be a bug in Blue Wallet, I imported the said wallet to BlockChain.com iOS App, but the unconfirmed transaction was not even shown there.
In short, how can I CPFP my transaction now?

## php – Is having 3 return types for a function, in order to facilitate error handling a bad idea?

I have a function which returns either `true/false`, each return plays nicely with the function name: `isOnline`, however, there are cases in which I want to throw an error inside of it. Maybe the status server isn’t available or what-not. But the problem is, errors in PHP are not that well-supported, nor is the community to keen about them. A `try/catch`is a foreign concept to most, so, I need to return a custom `ErrorObject`. So, your code ends up looking something like this:

``````\$online = isOnline();

if( !\$online ) {
return False;
}

if( gotError( \$online ) ) {
//Return the error or do something, execution stops here.
}
``````

I personally like it. While verbose, I genuinely never found this level of error checking to be exhaustive or to slow-down development, but a function that has more than 2 return possibilities just feels wrong.

Is there any literature/thoughts about returning errors?

## set theory – Can be this “handwaving” idea about “counting” reals somehow put on solid ground?

We know that the Cantor’s cardinality of a countable set is $$aleph_0$$ and the cardinality of continuum is $$2^{aleph_0}=aleph_0^{aleph_0}$$. Unfortunately, this measure is based on the idea of bijection, so sets of different volume can have the same cardinalities.

On the other hand, there is an idea of “numerocities” (which requires ordered or metric space), linked to the divergent integrals and series. For a subset of non-negative integers $$S$$ the numerocity is represented by a generally divergent series:

$$sum_{k=0}^infty p_S(k)$$

where $$p_S(k)$$ is the membership function, equal to $$1$$ if $$kin S$$ and $$0$$ otherwise. It allows to compare (using properties of divergent series) such sets as even and odd numbers, prime numbers, etc, giving more precise notion of the set’s size than cardinality.

The question is, can we somehow introduce a concept similar to numerocity to the uncountable sets, in such a way that it would reflect the volume of those sets? In other words, the set $$(0,2)$$ should have twice he numerocity of $$(0,1)$$. This is desirable…

First, let us agree on some symbols. Let use $$omega_-=sum_{k=1}^infty 1$$ for numerocity of natural numbers, and $$omega_+=sum_{k=0}^infty 1=omega_-+1$$ for numerocity of non-negative integers.

The following is pure handwaving, please don’t beat me hard.

First, let us consider the binary representation of the reals from $$(0,1)$$:
$$0.1101001…$$. Here each digit can be either $$0$$ or $$1$$. Since we start from position $$1$$ and have positions corresponding to all natural numbers, we can say we have $$omega_-$$ positions. So, the whole numerocity is $$2^{omega_-}$$.
Of course, if we take another base rather than $$2$$, we will have different expression for that numerocity. But this should not be confusing because numerocity is often dependent on ordering and filtering. So, if we make the same infinite set more dense, its numerocity changes (grows).

Can we somehow establish the expression for numerocity of reals on an interval, that would not depend on the chosen base for representation?

As I see it, the only way to avoid dependence on the base is to allow the base to go to infinity. So, we transcend to a representation in an infinite base. The digits start from $$0$$ but can be any natural number. As such (because we start from $$0$$), we have $$omega_+$$ digits. And the whole numerocity is $$omega_+^{omega_-}$$. Please don’t ask me how a particular number would be represented in such system. One can think of it as of some kind of limit. Also, since we do not have the biggest digit, the number $$1$$ does not belong here, so this numerocity represents the range $$(0,1)$$ rather than $$(0,1)$$.
I would point out that the expression of the form $$omega_+^{omega_-}$$, $$omega_-^{omega_-}$$ etc, often appear in the theory of divergent series, so this is not something “unseen”. It also fits well with the similar expression for the cardinality of continuum, which is a similar but less refined measure.
The numerocity of the whole real line then would be expressed as $$(omega_++omega_-)omega_+^{omega_-}$$.

I understand, these are very loose deas, particularly the idea of “infinite base” for a digital representation is unjustified. But I wonder whether some grains of it can be put on solid ground.

## client – Can someone explain the idea of using “body activity data” as proof of work in future systems?

As described in a patent filed by Microsoft,

Human body activity associated with a task provided to a user may be used in a mining process of a cryptocurrency system. A server may provide a task to a device of a user which is communicatively coupled to the server. A sensor communicatively coupled to or comprised in the device of the user may sense body activity of the user. Body activity data may be generated based on the sensed body activity of the user. The cryptocurrency system communicatively coupled to the device of the user may verify if the body activity data satisfies one or more conditions set by the cryptocurrency system, and award cryptocurrency to the user whose body activity data is verified.

It appears that the condition refered to would be simulated by a machine learning algorithm in order to check that the work was indeed done in real life by a person. Is this more like a reward system for doing certain monitored tasks, such as riding a bike in the black mirror episode https://en.wikipedia.org/wiki/Fifteen_Million_Merits?

Thanks