A superkey or super-key is defined in the relational model of database organization as a set of attributes of a relation variable for which it holds that in all relations assigned to that variable, there are no two distinct tuples rows that have the same values for the attributes in this set. The set of all attributes is a trivial superkey, because in relational algebra duplicate rows are not permitted: rows are a set no duplicatesnot a multiset duplicates allowed.
The superkey is also known as superset key. If attribute set K is a superkey of relation Rthen at all times it is the case that the projection of R over K has the same cardinality as R itself. A superkey is a set of attributes within a table whose values can be used to uniquely identify a tuple.
A candidate key is a minimal set of attributes necessary to identify a tuple; this is also called a minimal superkey. Given an employee schema consisting of the attributes employeeID, name, job, and departmentID, where no value in the employeeID attribute is ever repeated, we could use the employeeID in combination with any or all other attributes of this table to uniquely identify a tuple in the table.
The last example is known as trivial superkey, because it uses all attributes of this table to identify the tuple. In a real database we do not need values for all of those attributes to identify a tuple. This is a minimal superkey —that is, a minimal set of attributes that can be used to identify a single tuple. Second, eliminate all the sets which do not meet superkey's requirement. Finally, after elimination, the remaining sets of attributes are the only possible superkeys in this example:.
In reality, superkeys cannot be determined simply by examining one set of tuples in a relation. A superkey is a property of a relation variable which must hold for all possible values and can only be determined from the functional dependencies which apply to that relation variable.
If a relation contains 'n' attributes then maximum number of superkeys possible is 2 n. For example:. There are four superkeys in President:. From Wikipedia, the free encyclopedia. This article is about the database design term. For the keyboard button, see Super key keyboard button. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. Tata McGraw-Hill. Database management systems. Administration Query optimization Replication.This article provides a list of not commonly known default keyboard shortcuts and provides information about user customization.
There are several low level shortcuts that are implemented in the kernel which can be used for debugging and recovering from an unresponsive system. Whenever possible, it is recommended that you use these shortcuts instead of doing a hard shutdown holding down the power button to completely power off the system.
To use these, they must first be activated with either sysctl kernel. Values greater than 1 can be used to partially enable certain features, see the Linux kernel documentation for details. If you wish to have it enabled during boot, add the appropriate setting to your sysctl configuration. See Wikipedia:Magic SysRq key for more details. See Linux console Keyboard shortcuts. Readline is a commonly used library for line-editing; it is used for example by BashFTP, and many more see the details of readline package under "Required By" for more examples.
It has Emacs -like and vi -like editing modes which can be customized with escape sequences. Zsh uses ZLE to link shortcuts to widgets, scripts and commands. When we are in a graphical environment we may want to execute a command when certain key combination is pressed i. There are multiple ways to do that:. A simple X hotkey daemon with a powerful and compact configuration syntax.
See sxhkd for details. From actkbd home page :. A sample configuration and guide is available here. The factual accuracy of this article or section is disputed.
This article or section needs expansion. Users who prefer to work with the keyboard rather than the mouse may benefit from a key binding to the paste operation of the middle mouse button. This is especially useful in a keyboard-centered environment. A workflow example is:. The key codes for keys other than F9 can be determined using xbindkeys -k.
In the xmonad window manager there is a built-in function to paste the x-selection-buffer content.
In order to bind that function to a key-stroke here Insert key the following configuration can be used:. Redirected from Keyboard Shortcuts. Note: Please be aware that "REISUB" itself is just a mnemonic thing, is not any kind of general recommendation of key press sequence to take back control of unresponsive system, you shouldn't blindly press in this sequence each time without knowing their actual function as noted below.
On laptops that use Fn key to differentiate SysRq from PrtScrnit may not actually be necessary to use the Fn key i. You may need to press Ctrl along with Alt.
Discuss in Talk:Keyboard shortcuts. Reason: Why the ms delay?
In some applications, these two buffers are mirrored. Note: Depending on your X configuration, you may need to drop the -xsendevent argument to xvkbd.I don't think you need anything in xorg. In fact, I've done nothing but plug in the mouse, install xbindkeys and xte, and enter that config. Maybe try modifying your xorg. Sorry to reply to this Solved issue but I got the same problem.
Got myself a new MX Performance and I can't make the button 10 and button 13 work with anything. Then installed xbindkeys and produced a default config to my home directory. I made sure the xbindkeys were running and when I tried the xte commands from the terminal it worked fine.
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I know it's a little late for a response but I ran into the same issue today and here's what I did. That worked like a charm! That need to be wiki-ed, I am sure I will be searching for that again Atom topic feed.
Arch Linux. Index Rules Search Register Login. You are not logged in. Topics: Active Unanswered. Re: [SOLVED] MX performance and xbindkeys please any more ideas couse i am ready to make again a clean install maybe something is wrong with fontconfig-ubuntu from Aur and xvkbd is given errors nobody have logitech and xkeybindings? Any ideas or alternatives? Pages: 1. Atom topic feed Powered by FluxBB.Supra provides a cutting edge electronic lockbox system to the real estate industry.
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Windows equavalent keyboard shortcuts in Ubuntu
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Super User is a question and answer site for computer enthusiasts and power users. It only takes a minute to sign up. I want to disable the first row with Fn keys but keep the backspace, so I figured I could switch it with Delete since nopony is using it nowdays anyway. So I asked the xvkbd author - Tom Sato and he responded that the layout can be redefined with Xresources like. Thoug I haven't tested it as I already have the patch in place which is super easy on gentoo and have no reason to switch.
Sign up to join this community. The best answers are voted up and rise to the top.Part 3.11 Super Key Candidate Key Primary Key in DBMS in HINDI Types of keys in dbms in hindi
Home Questions Tags Users Unanswered. How to switch Backspace key with Delete key in xvkbd? Ask Question. Asked 6 years, 5 months ago. Active 6 years, 3 months ago.
Viewed 1k times. I ended up patching the source code but I'd like to know if there is another way. Active Oldest Votes. So I asked the xvkbd author - Tom Sato and he responded that the layout can be redefined with Xresources like xvkbd.
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If a window appears, your shortcut is correctly set. The issue is instead almost certainly the desired command:. In my experience, the use of XSendEvent is unreliable. Your xvkbd may have similar options. When sending key-sequences, you need to clear the current modifiers in order to ensure you are sending the sequence you want e. Further, xdotool at least has a strange behavior where if it sends events too soon, they disappear. In any case, you can get around this at least in xdotool with a delay:.
The type subcommand has a --delay option in case the initial delay is not sufficient to prevent dropping events. If you don't mind clobbering your clipboard, a better approach might be to send the default shortcut for paste selection :.
It then synthesizes the key sequence to paste this selection. As this requires only two synthesized keypresses, it is less likely to drop events than the other method. If you are trying to send key input to a specific window, and it does not appear to be working, then it's likely your application is ignoring the events xdotool is generating. This is fairly common. Sending keystrokes to a specific window uses a different API than simply typing to the active window.
If you specify 'xdotool type --window hello' xdotool will generate key events and send them directly to window However, X11 servers will set a special flag on all events generated in this way see XEvent. Many programs observe this flag and reject these events.
It is important to note that for key and mouse events, we only use XSendEvent when a specific window is targeted. Some programs can be configured to accept events even if they are generated by xdotool. Seek the documentation of your application for help. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered.
Linux: xvkbd tutorial
No more keyboard shortcut possible based on 'super' key aka 'windows' in any WM Ask Question. Asked 2 years, 2 months ago. Active 2 years, 2 months ago. Viewed times. I try with kde, gnome, xfce4, none works totally.
Anyone knows what's wrong?Ten Minute Events In-PlayBets are settled on the number of events occurring in the specified ten-minute time period. Time periods 41-50 and 81-90 include any added time. Events only count within the period they are taken - not awarded. In case of abandonment any bets on uncompleted time periods will be made void unless settlement of bets is already determined. Note that for the 10 minute free-kicks market a penalty does not count as a free-kick.
Corners, throw-ins, goal-kicks and free-kicks that have to be re-taken only count as 1. Foul throw-ins do not count. In the event of an abandoned match then bets for that match will be void. Otherwise, if the match is postponed or abandoned without both teams scoring, all bets will be void. Bets will be void if the match is abandoned unless settlement of bets is already determined. Divisional GoalsA minimum of four matches must be played for bets to stand. Abandoned or postponed matches will be attributed 2.
Total Goal MinutesPredict the aggregate time of all goals scored in the match, e. Any goals scored in first half added time count as 45. Any goals scored in second half added time count as 90. Should a dispute arise as to the time of any goal then the time provided by the PA will be deemed the time for settlement purposes. If a match is abandoned then all bets will be made void apart from those that have already made up (e.
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For example, following 2 yellow cards and 1 red card, the next card is deemed to be the 5th card. Next Goal MethodFree-kick - Goal must be scored directly from the free kick. Deflected shots count provided the free-kick taker is awarded the goal. Also includes goals scored directly from a corner kick.
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