What is the three paradigms of database?
The three paradigms of the database are: 1. Ensure that each column in the relational database is an atomic value that cannot be subdivided, that is, each column cannot be decomposed into smaller data items; 2. When satisfying the On the basis of the first normal form, eliminate the partial dependence of non-primary key columns on the primary key; 3. On the basis of satisfying the second normal form, eliminate the transitive dependence between non-primary key columns.
Database Three Normal Forms is a design specification used to standardize the data structure in relational databases. It was proposed by Edgar F. Codd in 1970 and is one of the important principles of database design. The goal of the three paradigms is to eliminate redundant data and improve database performance and data consistency.
Three normal forms can be divided into the following three levels:
First normal form (1NF): Ensure that each column in the relational database is an atomic value that cannot be subdivided, that is, each Columns can no longer be broken down into smaller data items. Ensure the atomicity of data.
Second Normal Form (2NF): On the basis of satisfying the first normal form, it eliminates the partial dependence of non-primary key columns on the primary key. That is, every non-primary key column must be completely dependent on the primary key. Contain only one primary key in each table by moving non-primary key columns to the new table.
Third normal form (3NF): On the basis of satisfying the second normal form, eliminate the transitive dependence between non-primary key columns. That is, if a non-primary key column depends on other non-primary key columns, it must be moved to a new table. This avoids data redundancy and data update anomalies.
The advantage of the three paradigms is that it can improve the performance and data consistency of the database. By formalizing the data structure, redundant data can be reduced, storage space saved, and data retrieval and update efficiency improved. In addition, the three paradigms can also improve the maintainability of data and ensure the consistency and integrity of data.
However, the three paradigms also have their limitations. In some cases, in order to improve query performance, redundant storage of data may be required, which conflicts with the normalization principle of the three paradigms. In addition, the three paradigms may also complicate data operations and increase the difficulty of database design and maintenance.
Summary:
The three normal forms of database are a design principle used to standardize the data structure in relational databases. It provides an effective database design method by eliminating redundant data, improving database performance and data consistency. However, in practical applications, it is necessary to weigh the limitations of the three paradigms and actual needs according to the specific situation, and choose the appropriate design method
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