A lot of friends in the tuning with MySQL will certainly use the explain to see the execution of the SELECT statement, here is a brief introduction to the results of the meaning of the two columns.1 Type column The official saying that this column represents the "type of access", and more commonly, the way MySQL finds the data rows needed. One is to introduce the worst from the most efficient to the best: all this is called a full-table scan, and no i
Meaning of DBUnitdb, or decibel, is a very common unit in the field of electronics. This unit is characterized by the use of logarithms to represent the original data. 1 shell = 10 db = 10dB = 10 times times PowerFor an amplifier,power Magnification Ap = ten lg (PO/PI)voltage Magnification Au = LG (UO/UI)current Magnification Ai = LG (IO/II)For example: amplifier magnification of 40dB, indicating that its voltage amplification is 100 times times, curr
Option meaning of info. plist, meaning of info. plist
1. application does not run in background (container name: UIApplicationExistsOnSuspend) from the end of iOS4.0, when you apply the program line, press Home terminal, the application does not parse the current line, but hides in the background. Therefore, if you want to download the current program line after you press Home then, check this option.
2. A
This may be used in the shell, including DOS.Null is something called a null bucket, and the benefit of redirecting the output to it is that the file size is not constantly increasing due to too much content in the output. In fact, you think that null is nothing, that is, the output of the command is discarded.1 indicates standard output, 2 indicates standard error output, 2>1 indicates the standard error output is redirected to standard output, so that the normal output and error output of the
The meaning of the forest root domain in the domain tree, and the meaning of the domain forest root domain
Contoso has many IT resources in the company's IT environment, and these IT resources are all in a state of decentralized management, which virtually increases the management cost of contoso, moreover, the management system cannot be implemented in the actual production environment.
So how can we solv
Yes HL7 The data of the Information Model is finally exchanged through XML. XML messages or files used for exchange are restricted by the schema corresponding to the model.
The idea of establishing a health archive information model is:
(1)
Rsp_k23 messages include MSH, MSA, err, qak, qpd, and PID segments. Err and PID are optional.1. When the MSA has an err, the err segment is filled with detailed information about the error. 2. when MSA is AA and qak is OK, PID is not empty;
Meaning of "modal verb +have+ done"1, must has the meaning of done. "Must have+ past participle" means speculation in the past, meaning "must have been, presumably already, must have been ...", only used in affirmative sentences. For example:The streets is wet. It must has rained. The street is wet, it must be raining.He must has been drinking beer. He must have
8th: The meaning of the pursuit of lifeThe author of the Quest for life is a psychiatrist who comes out of a concentration camp, with the energy of a concentration camp, creating a sense of treatment (legotherapy), which is less retrospective and less introspective, and its focus is on the future, In the work and meaning that the patient is going to accomplish in the future. People who know how to live, alm
Thoughts on the meaning of living out of lifeWith the teacher's recommendation, I read Victor Frankel's work, "living out the meaning of life," which describes the pain and suffering that the author has experienced, depicting such a horrible inferno from an impersonal point of view, and Aftermath's author has changed his mind about human life and pioneered the "meaning
Life---meaning. It seems to be a bit esoteric, and indeed quite esoteric, but it is not incomprehensible, because watching Victor Frankel's "living out the meaning of life" is more or less self-conscious. Life, human life down is his meaning, is the so-called inborn I will be useful, can not give up, did not give up there is hope, even if only a little, but give
This book is about the Nazi period, as Jews, Frankel's family were imprisoned in Auschwitz, his parents, wives, brothers, all died in the gas chamber, only he and his sister survived. Frankel not only beyond this purgatory pain, but also his experience and academic integration, to create a sense of treatment, for people to find the meaning of regeneration, but also left the history of human nature the most glorious testimony.After reading this book, f
Main content:
What is least squares
The geometrical meaning of least squares
Orthogonal projection matrix
What is least squares?Suppose we have n-pairs of data on our hands, {(Xi,yi): I=1...N}, in order to explore the relationship between the Y-variable and the X-variable, we want to match it with a polynomial, but how are the coefficients in the polynomial determined? It's definitely not going to work, and the least squares meth
As a hard-pressed engineering student, "Signal and system" + "digital signal processing" is not the past, a variety of headache concepts and mathematical formula: Fourier variation, Laplace change, Z-transform, convolution, cyclic convolution, autocorrelation, cross-correlation, discrete fourier changes, discrete fourier time changes ...Some time ago in the discovery of an interesting example, vividly explain the physical meaning of convolution, and t
What is the meaning of life? What is the meaning of living? Perhaps this problem is too deep for us to understand what life means and why we live, but it is a question that needs our constant consideration.The famous psychologist Frankel was a marvel of the 20th century. During the Nazi period, as a Jew, his family was imprisoned in Auschwitz, his parents, his wife, his brother, all died in the gas chamber,
1 Go home on the train, accidentally heard next to the little girl crying while calling family, she said: "Mom, sorry, originally said to make money to go home ..." she curled up in her seat and tried to suppress her cries, "but I did my best, mom, I don't regret it." ” Reminiscent of a previous reading of a log, some people say he has never believed the meaning of hard struggle. But is the meaning of
horse in uniform; the oral English usually refers to the competitor of the competition. Paper tiger is often used in China and Southeast Asian countries as powerful and weak enemies. The phrase ride the tiger indicates living in a very uncertain or dangerous way. 4. Rabbit-hare in British slang, Hare refers to people who do not buy tickets by car. The phrases that consist of hare are: Make a hare of sb. fool someone. Start a hare. The branch issues are raised during the discussion. For example,
1, why the Fourier transform, what is the physical meaning of it?Fourier transform is a very important algorithm in the field of digital signal processing. To know the meaning of Fourier transform algorithm, we must first understand the meaning of Fourier principle. Fourier principle shows that any continuous measurement of the timing or signal, can be expressed
Deep understanding of html5 tag meaning
Introduction:
I believe everyone is familiar with html5, but what is its true significance in specific development? What new definition and concept does html have? Why do some experts believe that after html5 is fully completed, all work can be achieved in the real cloud mode? Have you understood this series of questions?
This series of articles will answer all the things you don't know about html5 and html. The
The frequency of the image is the index of the intensity of the gray intensity in the image, and it is the gradient of the gray level in the plane space. such as: a large area of the desert in the image is a region of slow gray-scale changes, the corresponding frequency value is very low, and for the Surface attribute transformation of the sharp edge region in the image is a sharp change in the area of gray, the corresponding frequency value is higher. Fourier transform has a very obvious physic
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