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This article mainly introduces what the logical structure of data in the relational database refers to. It has a certain reference value, and interested friends can refer to it. I hope you will gain a lot after reading this article. Let the editor take you to understand it.

The data logical structure in a relational database is a two-dimensional table. Tables in relational databases use two-dimensional tables to store data, which is a logical group with related information arranged by rows and columns. A database can contain any number of tables.

The data logical structure in a relational database is a two-dimensional table.

Related introduction:

Relational database is the mainstream of database application, and the data models of many database management systems are developed based on relational data models.

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. Properties (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 represents a property value, such as "Database principles" is the property value of the course name.

5. Master 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). For example, the above relationship can be described as: course number, course name, credits, teacher).

However, this simple data structure of the relational model can express rich semantics and describe the entities and the relationships between entities in the real world.

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