Definition Of Primary Key And Foreign Key In Database

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

If a computer manufacturer, its database holds machine and accessories product information. The table used to save the whole product information is called pc; the table used to save the parts supply information is called parts. There is a field in the pc table, used to describe the type of CPU used in this computer; there is a field in the parts table, the description of the CPU model, we can think of it as a list of all CPU models. Obviously, the CPU used by this manufacturer must be a model that exists in the supply information sheet. At this time, two tables ...

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As a business person, you may have to travel by air frequently. If one day, when you sit on the plane, in the absence of any prior request, a smiling stewardess will be a cup of fresh green tea in front of you, you must not be surprised. Because by sorting and analyzing your previous flight information, the airline will be able to understand the various preferences of your flight and provide you with attentive service. This is not a myth. According to the reporter understand, some domestic airlines are doing this research, hope that through the detailed analysis of passenger data to achieve ...

Innovative report from the dean of top research institutes when all our actions and our lives can be "data", the company that holds the data is like owning a rich gold mountain. 　　As Victor Maire-Schoenberg says, the big data age is "the future that has happened," and in this already-occurring future, there is no bystander. December 19, 2013, by the boutique media "digital Business Times" sponsored by the "Great data creation of the era of Subversion" 2013 China Summit Forum in Beijing to make a grand Holiday Crowne Plaza Hotel ...

According to foreign media reports, the United States "Time" magazine every year will be the most personalized list of websites. These sites on the list are both interesting and informative, and can help you save time and money and may even change your life. As in previous rankings, most of the 50 most personalized web sites on the magazine's list are still obscure. 　　The editors of Time magazine have found that these sites are not only interesting, creative and appealing, but also helpful to you. 1. LastPass website security experts say your ...