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This article mainly introduces "what are the main functions of DBMS". In daily operation, I believe many people have doubts about the main functions of DBMS. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "what are the main functions of DBMS?" Next, please follow the editor to study!

(1) data definition function: provides data definition language (DDL) to define all the features and attributes of the database, especially row layout, column definition, key column (sometimes key selection method), file location and storage strategy, including commands:

DROP (delete database) delete database: drop database if exists database name

CREATE (create database) create table: create table if not exists table name (column name constraint)

ALTER (modify database) add column name: alter table table name add column name constraint

Modify column name: alter table table name change old column name new column name data type

Modify column field data type: alter table table name modity column name data type

Delete column name: alter table table name drop column name

Modify table name: alter table table name rename new table name

GRANT (Grant permissions)

REVOKE (remove permissions from the current user or group), TRUNCATE (delete only all data in the table, do not delete the structure of the table)

Note: the truncate table command quickly deletes all records in the data table, but retains the data table structure. This kind of quick deletion is different from the output of the delete from data table, the data deleted by the delete command will be stored in the system rollback segment, and the data deleted by the truncate command can be rolled back when needed, while the data deleted by the truncate command is not recoverable.

(2) data manipulation function: provide data manipulation language (DML)

Manipulate data to achieve basic operations on the database:

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SELECT (query) select from table name where condition (condition 1 and condition 2) INSERT (insert) insert into table name (column 1, column 2) values (','), (','), (',') DELETE (delete) delete from table name where condition UPDATE (modify) update table name set column name ='', column name = 'where condition

(3) Operation and management of database

A. Ensure the security and integrity of the data.

B. concurrent use of data by multi-users

C. System recovery after failure

(4) Database establishment and maintenance function (utility)

A. Bulk loading of database data

B. Database dump

C. Repair of media failure

D. Reorganize the database.

E, performance monitoring

At this point, the study on "what are the main functions of DBMS" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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