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December 29

Question about our SQL tutorial

I'm asking this here, since I presume we have more traffic here than on Wikibooks. SQL Exercises/The computer store has a number of exercises with inner joints that actually look easier without, such as "Select all the data from the products, including all the data for each product's manufacturer.". What's the benefit of adding INNER JOINT? The result should be the same, right? — Sebastian 07:34, 30 December 2015 (UTC)[reply]

Yes, they are the same and both will work, and the comma is a JOIN operator, but was used before the actual JOIN operators were added to SQL. Some people prefer to use JOIN operators instead of commas as the query is a bit more readable (also using the ON clause rather than WHERE), it explicitly states which kind of join it is, and using commas is the older standard. --Canley (talk) 09:11, 30 December 2015 (UTC)[reply]

Also note that while making a curriculum, you want to cover all the material, and sometimes this means exercises done to show some feature, even if you would personally do it another way. StuRat (talk) 18:34, 30 December 2015 (UTC)[reply]

Using the select … from … where … in (select … from) is low performance on the SQL server. Using joints is move effective. In the products table, the manufacturer is not an unique entry. Finding the one record that fits, You dont want the whole list. You only wanna pick or agregate data from the record that fits Your specified critria. For that reason You are using left join and right join. Use MS-SQLExpress, MS-Access or LibreOffice/OpenOffice Base to draw such queries. Then view the SQL source, You have "drawn". --Hans Haase (有问题吗) 12:13, 31 December 2015 (UTC)[reply]

Factorization

Am I right that factorization of polynomials over finite field can be done efficiently (it's in $P$ ), while factorization of numbers is not in $P$ ? 213.8.204.30 (talk) 16:55, 30 December 2015 (UTC)[reply]

Ping User:PrimeHunter. I can't find a complete answer anywhere, but based on this thread I think polynomial factorization over a fixed field is in P, but if the degree of the field is part of the input then the best known deterministic algorithms are exponential (but there may be randomized polynomial-time algorithms).

No polynomial-time algorithms are known for integer factorization, and it's suspected that it's not in P, but there's no proof of that. All factorization problems are in NP and a proof that anything in NP isn't in P would imply P≠NP. -- BenRG (talk) 20:55, 30 December 2015 (UTC)[reply]

I don't know more than this. PrimeHunter (talk) 23:36, 30 December 2015 (UTC)[reply]

Thank you! 213.8.204.30 (talk) 19:42, 31 December 2015 (UTC)[reply]

Ugly characters in an edit summary

A few minutes ago, there was an edit to Wikipedia:Sandbox (the time said 18:28 using Wikipedia's clock at the time of the edit) where the edit summary had the ugly characters ṇ̴̩̻̳̲̥̹̻͖̦̺̥͇͔̺̦̻̔͆̅ͯ̔̀͘wͮͮ̄̿̈́ͫ͋̂̈́͏̢̹͕̭̪̺̲̝̖̣̩ͅͅo̶͈̜̹̬̰̮̺͊͑̇̉͒ͫ̾ͬ̔ͮ̃́̀̔̉͗ͩ͟͝e̿̎̐̓̊̓̓̽̑̾ͭ̌̓͛͑̓̀̉̽͏̪̙̭̘̪̜̫͍͈̰͎̣̫̝̥̗͜͢r̴̢ͤͥ. How did these ugly characters become possible to type?? Georgia guy (talk) 18:36, 30 December 2015 (UTC)[reply]

Note that I see them reproduced here (in case others don't). StuRat (talk) 18:48, 30 December 2015 (UTC)[reply]

But I didn't manually type them; I copy-pasted them from the edit summary. Georgia guy (talk) 18:52, 30 December 2015 (UTC)[reply]

First, what the characters are is combinations of a base character with a bunch of combining characters that can be used to add accents. For example, as well as providing a single character É (code point 00C9), Unicode provides separate characters for the E (0045) and the "combining acute accent" (0301), which will add itself to the preceding character. (There is also a non-combining acute accent (´), code point 00B4.) So someone has been playing games with using a whole lot of combining characters with the same base character to see what the result looked like.) Second, how they typed them: I have no idea. But in principle, the same way they type other Unicode characters in their particular environment. --76.69.45.64 (talk) 19:09, 30 December 2015 (UTC)[reply]

This is often called Zalgo text, and the editor likely used a Zalgo text generator to make it. Surprisingly, there's no English Wikipedia article on it. Maybe someone should translate the Dutch article. -- BenRG (talk) 21:07, 30 December 2015 (UTC)[reply]

It's weird. .

. Z̵͈̺͓̜̣̓͌̉̓̏̏͝ą̛̺̩̼̝̤͉̪̮̾̎̈́̐̒̾̚͘͢͠l̴̻͖͇̗̞͋̀̈̑̇̌̎̊̕g̛̜̳̼̫̞̍͆̃̓̈̃̚͠͝o̷̭̝̗͇̣̜̅̐͆͒̈́̎̄͑̐͡ . .

The actual characters above seem to be "Z£#794;£#849;£#794;£#829;£#859;£#778;£#832;£#794;£#776;£#784;£#840;£#828;£#854;£#815;£#839;£#804;£#810;£#828;£#839;£#805;£#822;a£#832;£#780;£#856;£#855;£#849;£#832;£#794;£#804;£#837;£#814;£#807;£#790;£#806;£#841;£#828;£#823;l£#784;£#795;£#787;£#835;£#859;£#794;£#832;£#768;£#796;£#826;£#845;£#810;£#806;£#863;£#805;£#792;£#851;£#854;£#823;g£#862;£#834;£#849;£#788;£#831;£#785;£#859;£#849;£#857;£#799;£#846;£#857;£#854;o£#794;£#783;£#830;£#856;£#788;£#768;£#794;£#855;£#788;£#812;£#790;£#839;£#827;£#839;£#805;£#803;£#820;" except that I've had to replace "&" with "£" because "nowiki" doesn't work.

Do we have anyone who can do the translation? Google does quite well, but perhaps someone is familiar with both Dutch and the topic? Dbfirs 20:06, 31 December 2015 (UTC)[reply]

Another decent explanation on stackoverflow. —Steve Summit (talk) 10:16, 2 January 2016 (UTC)[reply]

Thanks for that link. The nearest article in Wikipedia is Combining character. Would it be best to add a section to that article, or to create a separate article on Zalgo? Please leave a note here if you are working on an article. Dbfirs 12:05, 2 January 2016 (UTC)[reply]

Bill Gates

Why didn't Bill Gates patient the PC? — Preceding unsigned comment added by Saberinmypants (talk • contribs) 19:11, 30 December 2015 (UTC)[reply]

The simplest answer is that he didn't invent the PC. Mingmingla (talk) 20:07, 30 December 2015 (UTC)[reply]

... and he didn't even invent the operating system that he sold. Dbfirs 21:32, 30 December 2015 (UTC)[reply]

According to this book, "[The US definition of patentability] made it difficult to patent most aspects of the IBM PC because it was designed using previously existing parts that anyone could purchase off the shelf" [punctuation sic], and "In what was later viewed as the perhaps the most costly business mistake in history, IBM failed to secure exclusive rights to the DOS it had contracted from Microsoft". So, the PC couldn't have been patented under US law as it wasn't sufficiently original, and Bill Gates did retain the rights to MS-DOS and made a bob or two in consequence. Tevildo (talk) 22:38, 30 December 2015 (UTC)[reply]

(Assuming you meant "patent"...) "PC" is a vague term. But even if you specifically mean the IBM PC, Gates didn't invent it (which you can probably guess if you know Gates never worked at IBM). Microsoft simply provided IBM with an operating system for it. History of the personal computer might be informative reading. And as noted above there's a whole separate issue that any PC is probably not patentable as a single invention, which is why IBM never had any patent on "the PC" either. Certain components or aspects of a specific product may be patentable, but not simply the concept of a computer designed for use by an individual (a concept that predated the IBM PC, in any case). --71.119.131.184 (talk) 22:59, 30 December 2015 (UTC)[reply]

The original IBM PC was essentially the same as any of dozens of CP/M 86 based computers. The BIOS ROM was so similar to that required by CP/M that I owned a machine that would dual-boot either CP/M or MSDOS and could run CP/M programs within a DOS session. Early versions of DOS were almost indistinguishable from CP/M. Read CP/M#MS-DOS_takes_over - I think you'll understand just how little Bill Gates contributed here. The only reason the IBM PC (and therefore MSDOS) succeeded so well was that it had the letters I, B and M on the front. Businesses had been scared of these tiny personal computers - they didn't understand what they were for or what they could do. When their beloved IBM proclaimed that this machine was "A Very Good Thing" - they flocked to it in droves. The IBM marketing was the only thing that made MSDOS the gold standard. The fact that Gary Kildall (owner of Digital Research who owned CP/M) dropped the ball and didn't work with IBM to get CP/M 86 onto the IBM PC is the single reason why Bill Gates and Microsoft got the start they did. SteveBaker (talk) 05:21, 3 January 2016 (UTC)[reply]

Windows Defender updates--the sequel

Referring to this question and another one that this question refers to, I selected two of the three updates just now (when I posted the question, before it was deleted without justification). Okay, now there are four. The first two have finished downloading but I haven't restarted the computer since then. We will see what happens. Anyway, I still had to do a startup repair on Sunday and don't know why since I never get specific messages about what happened. Tuesday, everything was fine. If everything works Thursday, I will download the other two, maybe one Thursday and one Friday, later this week.

And to satisfy the IP who had no right to delete this, I'm still trying to document what is going on or get answers. I'm not supposed to edit archives.— Vchimpanzee • talk • contributions • 17:12, 29 December 2015 (UTC)[reply]

Some updates don't need a restart. Are you still having problems, or are the unexpected bahaviours subsiding on your computer? Dbfirs 00:54, 31 December 2015 (UTC)[reply]

I was not told to restart this time, and I am downloading the largest of the updates. So far, no problems since Sunday.— Vchimpanzee • talk • contributions • 16:40, 31 December 2015 (UTC)[reply]

A possible clue to what might be going on is this. I got a message that an update failed. I should have made a note of the error message before telling it to try again. Anyway, it started at 37 percent. I don't know whether it is all right to continue downloading or whether I should just start over. I've had downloads stop in the middle. It's probably my slow Internet but I'm reluctant to upgrade.

Here's the information in my update history (oh, good, it includes an error message):

System Update Readiness Tool for Windows Vista for x64-based systems (KB947821) [October 2014]

Installation date: ‎12/‎31/‎2015 11:44 AM

Installation status: Failed

Error details: Code 80072EFE

Update type: Important

This tool is being offered because an inconsistency was found in the Windows servicing store which may prevent the successful installation of future updates, service packs, and software. This tool checks your computer for such inconsistencies and tries to resolve issues if found.

More information: http://support.microsoft.com/kb/947821

Help and Support: http://support.microsoft.com

It's at 43 percent now. The description of this update suggests it might fix the other problem. — Vchimpanzee • talk • contributions • 16:55, 31 December 2015 (UTC)[reply]

I share your problems of a slow internet connection, so I try to do major upgrades when I have access to a faster connection six miles nearer to the exchange. Perhaps most of your problems stem from the major rollback, meaning that there were lots of outstanding updates to complete. Usually, Windows eventually sorts itself out. Dbfirs 17:06, 31 December 2015 (UTC)[reply]

How can you possibly do updates six miles away? Anyway, I got the "failed" message again at 54 percent (same error message as above). It's now up to 58 percent as I had a hard time getting here again, especially when I noticed someone removed what I said here. I'm still asking for help and I probably need all this here in order to ask for further help from the person from Microsoft.— Vchimpanzee • talk • contributions • 17:29, 31 December 2015 (UTC)[reply]

With difficulty, which is why I borrow a faster connection. I assume that's not possible for you? Dbfirs 17:43, 31 December 2015 (UTC)[reply]

Failed at 64 percent, same error message. Restarted. And I see I'm downloading both updates now. Maybe nothing bad will happen.— Vchimpanzee • talk • contributions • 17:42, 31 December 2015 (UTC)[reply]

That error code (80072EFE) is usually caused by an interruption in your internet connection. Dbfirs 17:54, 31 December 2015 (UTC)[reply]

I figured that's what was happening. Failed again before 70 but up to 79 now. I don't know how I would do updates closer. I could ask about a higher speed but with TiVo and digital cable (that second one was not my choice) and a new modem I didn't actually need, until it became necessary for the TiVo, I've just had too much of these additional monthly costs.— Vchimpanzee • talk • contributions • 19:03, 31 December 2015 (UTC)[reply]

It sounds as if you already have a much faster internet service than I have, so perhaps there is some reason for the connection dropping out. Are you using WiFi? Dbfirs 19:17, 31 December 2015 (UTC)[reply]

No, I tried that with TiVo; it was fortunate I was having modem problems, which would have gone away if I had just plugged the thing in right. They decided the modem had gone bad and sent me a new one, so I have WiFi for the TiVo if I want it. But this computer has a cable. Instead of a percentage I now see "Installing update 1 of 1". When I go to the update history it says "failed" three times for the cumulative security update and five times for the system update readiness tool. This must refer to all the interruptions. I have a theory the interruptions might result from my trying to do other stuff at the same time as the downloads. But I have no place else to go. If the college library was open I could use the Internet or look at actual newspapers while downloading or doing the virus scan, so I won't slow down everything else.— Vchimpanzee • talk • contributions • 20:51, 31 December 2015 (UTC)[reply]

I just got the message "New updates are available". So I checked and the update failed. I was relieved that it was not the one I've been downloading all afternoon. My update history says I was successful. As for the cumulative security update, I'll wait until tomorrow.— Vchimpanzee • talk • contributions • 21:50, 31 December 2015 (UTC)[reply]

There are two new updates now, but I need to focus on the Norton tool today. Plus the security update is a huge file and I should wait for a day when I've got more time to deal with it.

And I can't go two days without some problem when the computer starts up. This time there was what looked like scrolling and the screen went black, but no beeping, and I couldn't turn the computer off but had to unplug it. After that all was well.— Vchimpanzee • talk • contributions • 19:00, 1 January 2016 (UTC)[reply]

So I followed the directions on the Microsoft web site. The Fixit tool fixed some problems but not others, as I will tell the person there. Windows update error 0x80070757 (2016-01-01-T-02_28_43P), and Problems installing recent updates.— Vchimpanzee • talk • contributions • 19:38, 1 January 2016 (UTC)[reply]

That's a rather worrying error message because it indicates a problem with a partition on your hard drive. Are you doing a major upgrade to a later version of Windows? Dbfirs 00:04, 2 January 2016 (UTC)[reply]

No. The computer is so old that would be pointless. I'm trying to keep it around as long as it will work. I dread having to get used to new things or do all the stuff that getting a new computer involves, or spend the money.

I got another blue screen today and don't know why. I was farther along in the startup process than I usually am. I was downloading an update, which I didn't mean to do. I clicked in the wrong place.— Vchimpanzee • talk • contributions • 17:12, 2 January 2016 (UTC)[reply]

And speaking of the hard drive, I saw a way to check it yesterday when I was investigating that error message. While I never found that specific code, I somehow ended up where I could check things but it would have required more time than I had. Maybe Monday.— Vchimpanzee • talk • contributions • 17:43, 2 January 2016 (UTC)[reply]

Can anyone explain to me what happened today? First, let me say the person from the Microsoft site gave up and referred me to the paid support service. There may be no point. I've never had this much trouble getting started. Two blue screens, one time everything froze, and one time the screen just went black. The last one came just after a message McAfee scanner quit working. It wasn't the "service host" like it usually is. All is well now, I guess. The first blue screen came with a message IRL_NOT_LESS_THAN_OR_EQ, or something like that. Then when I restarted, before I even got to where I could get on the Internet, ther were all these identical lines across part of the screen which appeared to be scrolling really fast but as if they were credits from 1950s TV series, not affecting what was in the background, except the word "Welcome" and the circle that is supposed to be turning round and round are stopped. I had to unplug the computer to restart it. Then came one more blue screen (which came first, that or the McAfee message which was followed by the screen going black, doesn't really matter). The message was PRN_LIST_CORRUPT. Maybe. PRN is a group of radio stations airing NASCAR. Anyway, I'm wondering if this is even something I can recover from. Even if I take the whole thing to the store, how much longer will the computer last? Is the expense worth it? I don't like unplugging the monitor because I was unable to plug it back in when I got a new one, broke the cable, and had to replace that, and I made sure the person at the store plugged it into the computer. With a new computer I know I have to go through it, so I hope I do it right.— Vchimpanzee • talk • contributions • 18:49, 3 January 2016 (UTC)[reply]