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2 Database design 2.1 Design contentĭatabase design belongs to the overall design and detailed design of the system. Each family owns one or more pieces of arable land, A piece of cultivated land belongs to one or more families. Įach family contains one or more family members, A family member belongs to only one family.
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The information of cultivated land includes the number of cultivated land （ Ownership code plus 4 Bit self coding composition ）、 Types of cultivated land 、 Sheet number 、 Patch number 、 Contract area 、 Measured area 、 Direct compensation area 、 Year of registration. Family member information including name 、 ID number 、 Gender 、 Date of birth 、 Age 、 Is the land obligor. Agricultural household information includes household number 、 Type of household 、 Name of the householder 、 Householder ID card number 、 Administrative division of household （ The ownership code ）. Īgricultural households need to manage data 、 Family members 、 Three kinds of information of cultivated land. In order to protect the cultivated land effectively, Chengdu Bureau of land and resources decided to establish the basic database of cultivated land protection in Chengdu, Establishing Farmers 、 Farmland archives to strengthen the management of farmland and subsidy fund. It's not hard to see that no matter how the data is organized, Different data models focus on two things ： Data and the connections between them. The biggest difference between the relational model and the former two is that the main code is used instead of the pointer to navigate the data. It can be divided into ： hierarchical model, The tree structure is used to represent the relationship between data, A node represents a record, Nodes other than the root node have and only one parent node Mesh model, Network structure is used to represent the relationship between data, Allow more than one node to have no parents, A node can have multiple parents relational model, Use table structure to express entity set and the relationship between entity sets. Memory type, Such as Session conversation. Database type, Such as SQL Server、Oracle、Sqlite etc. It can be divided into data storage forms ： File type, Such as XML、JSON、Cookie etc.
I want to use “ Quiet as a virgin, Move like a rabbit ” To describe data and code will be more vivid ： Data is a static snapshot of the recorded object at a certain point in time, For example, a form And the code that implements the business is an invisible hand, Manipulating and changing data. It can be seen that code and data are the elements of software.
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The software engineering book used to be equivalent to code plus data. Pay attention that I'm not lost, Share a little bit every day, Make a little progress every day ~ 1.1 The organization of data
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Big guy reveals secrets Java Where are people planted ？ Click to get it for free 《 Interview list of large factories 》, Overcome the interview difficulties ~> 1 summary
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