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This article mainly introduces which types of data operations in relational databases are divided into, which can be used for reference by interested friends. I hope you will gain a lot after reading this article. Let's take a look at it.

The data operation of relational database is divided into query and update. Query statements are used for various retrieval operations, and update operations are used for insert, delete, and modify operations.

A relational database is a database based on a relational database model, which deals with the data in the database with the help of concepts and methods such as set algebra. at the same time, it is also a group of tables with formal description. The essence of this form of table is to load a special collection of data items. The data in these tables can be accessed or reconvened in many different ways without the need to reorganize database tables.

The definition of a relational database results in a table of metadata or a formal description of tables, columns, ranges, and constraints. Each table (sometimes referred to as a relationship) contains one or more types of data represented by columns. Each row contains a unique data entity, which is the category defined by the column.

When creating a relational database, you can define the range of possible values of a data column and further constraints that may be applied to that data value. The SQL language is the interface between standard users and applications to relational databases. Its advantage is that it is easy to expand, and after the initial database creation, a new data type can be added without the need to modify all existing applications.

The data operation of relational database can be divided into two types: query and update. Query statements are used for various retrieval operations, and update operations are used for insert, delete, and modify operations.

Relational query languages are divided into two categories according to their theoretical basis:

1. Relational algebra language: query operation is a DML language based on set operation.

2. Relational calculus language: query operation is a DML language based on predicate calculus.

Relational databases are divided into two categories:

One is desktop database, such as Access, FoxPro, dBase, etc.

The other is client / server databases, such as SQL Server, Oracle, Sybase, etc.

Generally speaking, desktop database is used for small, stand-alone applications, it does not need network and server, it is more convenient to implement, but it only provides data access function.

The client / server database is mainly suitable for large-scale, multi-user database management systems, and the application program consists of two parts: one resides on the client and is used to display information to and interact with users; the other part resides in the server and is mainly used to realize the operation of the database and the calculation and processing of the data.

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