What is the purpose of SQL statements and what are the functions of SQL statements?

The foreground interacts with the data stored internally.

The background data is stored through a certain data structure, and in order to facilitate the frontend to access the data in these background data structures, the SQL syntax appears, through this"Channels"It's the front desk that communicates with the back office. (In the process of communication, the front desk does not need to know how the data is accessed later, what information is stored in the data).

I'm talking about it in layman's terms.

With SQL statements, you can:

1.Inserts data into a data table in the database.

2.Query one or more records based on your criteria.

3.Update a piece of data in the database according to your instructions.

4.Delete unwanted data records.

Statements support some special calculation functions, such as summarization, which allows you to easily summarize the values of a certain column.

Enough is popular. Let's break it up, hehe.

Query the data from the database according to the conditions you need and the way you want to display it.

1. The role of SQL:

1. SQL is mainly used for the query, summary, writing, deletion and other aspects of database series software, and is specifically used for database programming or database data maintenance.

2. In other words, SQL is generally used for database programming and troubleshooting of existing databases. Therefore, generally the programmers involved in the database or the maintenance personnel of the computer information system need to learn the knowledge of SQL (that is, the database).

1. SQL is a structured query language.

Structured Query Language).

2. At present, it is most mainly used in Microsoft.

SQL Server and Oracle Database.

Manipulation of data in the server. It is also often used as an interface instruction statement for other small databases and stand-alone databases, such as mysql and access.

3. In large-scale database applications, the SQL statements corresponding to specific functions are generally embedded into the program by program development designers, and when multiple complex SQL statements are required, they will also be written in the database server in the form of storage procedures and other methods for calling. Users often don't need to deal with specialized SQL statements.

SQL (Structured Query Language) is used to access data and query, update, and manage relational database systems.

SQL is based on relational algebra and tuple relational calculus, including a data definition language and a data manipulation language. The scope of SQL includes data insertion, querying, updating, and deletion, database schema creation and modification, and data access control. Although it is very much declarative programming (4GL), it also contains elements of procedural programming.

SQL was the first commercial language implementation of Edgar Cod's relational model, which was described in his influential 1970 article, "A Relational Model for Large Shared Databases."

Although SQL is not fully designed according to the Referential Model of Codd, it is still the most widely used database language. SQL became a standard of the American National Standards Institute (ANSI) in 1986 and an International Organization for Standardization (ISO) standard in 1987. Since then, the standard has undergone a series of updates to include a number of new features.