Shulou(Shulou.com)06/01 Report--

This article is to share with you about what sql means. The editor thought it was very practical, so I shared it with you as a reference. Let's follow the editor and have a look.

The full name of sql is structured query language (Structured Query Language), which is a special purpose programming language, a set of operation commands specially established for database, and a fully functional database query and programming language for accessing data and querying, updating and managing relational database systems, as well as an extension of database script files.

SQL is a high-level non-procedural programming language that allows users to work on high-level data structures. It does not require the user to specify the data storage method, nor does it require the user to know the specific data storage method, so different database systems with completely different underlying structures can use the same structured query language as the interface for data input and management. Structured query language statements can be nested, which makes it have great flexibility and powerful functions.

The structured query language SQL consists of six parts:

1. Data query language (DQL:Data Query Language):

Its statement, also known as a "data retrieval statement", is used to obtain data from a table and determine how the data is given in the application. The reserved word SELECT is the most frequently used verb in DQL (and all SQL). The other commonly used reserved words in DQL are WHERE,ORDER BY,GROUP BY and HAVING. These DQL reserved words are often used with other types of SQL statements.

2. Data manipulation language (DML:Data Manipulation Language):

Its sentences include verbs INSERT,UPDATE and DELETE. They are used to add, modify, and delete rows in the table, respectively. Also known as Action query language.

3. Transaction language (TPL):

Its statement ensures that all rows of the table affected by the DML statement are updated in a timely manner. TPL statements include BEGIN TRANSACTION,COMMIT and ROLLBACK.

4. Data Control language (DCL)

Its statements are licensed through GRANT or REVOKE to determine the access of individual users and user groups to database objects. Some RDBMS can use GRANT or REVOKE to control access to individual columns of the form.

5. Data definition language (DDL):

Its sentences include verbs CREATE and DROP. Create a new table or delete a table (CREAT TABLE or DROP TABLE) in the database; add indexes to the table, and so on. DDL includes a number of reserved words related to obtaining data in the human database catalog. It is also part of the action query.

6. Pointer Control language (CCL):

Its statements, such as DECLARE CURSOR,FETCH INTO and UPDATE WHERE CURRENT, are used for separate operations on one or more forms.

Thank you for reading! About what sql means to share here, I hope the above content can be of some help to you, so that you can learn more knowledge. If you think the article is good, you can share it and let more people see it.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.