What can each record in a relational database table do?

The order of records in a relational database table can be reversed arbitrarily without affecting the actual meaning of the data in the database. There are multiple records in a relational database table. The order between the records will not affect the data relationship in the database, so the order of the rows does not matter and can be reversed at will.

The operating environment of this tutorial: Windows 7 system, mysql version 5.8, Dell G3 computer.

The records in a relational database table can be reversed in any order without affecting the actual meaning of the data in the database.

Relational database is a database based on the relational database model. A relational database definition results in a table of metadata or a formal description of tables, columns, ranges, and constraints. Each table (sometimes called a relationship) contains one or more data types represented by columns. Each row contains a unique data entity of the type defined by the column.

Relationship model structure

1. Single data structure----relationship (table file). The table of a relational database uses a two-dimensional table to store data. It is a logical group with related information arranged in rows and columns. It is similar to an Excel worksheet. A database can contain any number of data tables.

From the user's perspective, 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 layman's terms, a relationship corresponds to a table.

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

There can be multiple records in the table. The order between the records will not affect the data relationship in the database. Therefore, the order of the rows does not matter and can be reversed arbitrarily.

3. Attributes (fields). Each column in the data table is called a field. 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 fields. When creating a data table, each field is assigned a data type, defining their data length and other properties. Fields can contain various characters, numbers, and even graphics. Such as error! Reference source not found.

4. Attribute value. The intersection of rows and columns represents a certain attribute value. For example, "Database Principles" is the attribute value of the course name

5 and the main code. The primary key (also called the primary key or primary key) is the data used to uniquely identify a tuple in the table. Keywords are used to ensure the uniqueness of records in a table. They can be one field or multiple fields and are often used as index fields of a table. The key of each record is different, so it can uniquely identify a record. The key is also called the primary key, or simply the primary key. Such as error! Reference source not found.

6. Domain. The value range of the attribute.

7. Relationship model. The description of relationships is called a relationship 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 (course number, course name, credits, teacher).

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