What is the data structure used in relational database systems?

Editor to share with you what the data structure used in the relational database system is. I hope you will get something after reading this article. Let's discuss it together.

The data structure used in relational database systems is two-dimensional tables. In the relational database system, all the data is represented by the structure of two-dimensional tables, which are usually called relationships. In a relational database, each relationship is a two-dimensional table.

Parsing:

In the relational database system, all the data is represented by the structure of two-dimensional tables, which are usually called relationships. In a relational database, every relationship is a two-dimensional table, and both the entities themselves and the relationships between entities are represented by a two-dimensional table of "relations".

Relational model structure

1. Single data structure-relationship (table file). Tables in relational databases use two-dimensional tables to store data, which is a logical group with relevant information arranged by rows and columns, which is similar to Excel worksheets. A database can contain any number of tables.

From the user's point of view, the logical structure of a relational model is a two-dimensional table, consisting of rows and columns. This two-dimensional table is called a relationship. In popular terms, a relationship corresponds to a table.

2. Tuple (record). A row in a table is a tuple, or a record.

3. Attributes (fields). Each column in the data table is called a field, and the table is defined by the various fields it contains. Each field describes the meaning of the data it contains. The design of the data table is actually the design of the field. When you create a data table, you assign a data type to each field and define their data length and other properties. Fields can contain a variety of characters, numbers, and even graphics.

4. Attribute value. The intersection of rows and columns indicates an attribute value, for example, "Database principle" is the attribute value of the course name.

5. Main code. A master code (also known as a primary key or primary keyword) is the data in a table that is used to uniquely determine a tuple. Keyword is used to ensure the uniqueness of records in a table, can be one or more fields, and is often used as an index field for a table. Each record has a different keyword, so it can uniquely identify a record. The keyword is also called the primary keyword, or primary key for short.

6. Domain. The range of values for the property.

7. Relationship model. The description of a relationship is called a relational schema. The description of the relationship is generally expressed as: relationship name (attribute 1, attribute 2. Attribute n).

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