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Introduction to DML, DDL and DCL

What is it?

DML: data manipulation language

Including addition, deletion, modification and search (INSERT,DELETE,UPDATE,SELECT), a language for manipulating data. The operating unit of DML is RECORD.

INSERT, that is, insert one or more records.

DELETE, that is, delete one or more records.

UPDATE, that is, what is recorded in the update table.

DDL: data definition language

Commonly used are CREATE,ALTER,DROP, etc. DDL is mainly used to define tables or change table structure, data types, links and constraints between tables and other initialization work. DDL is used to manipulate the properties of objects and objects, including the database itself and database objects: tables, views, and so on. DDL does not operate on the data content.

CREATE, you can create a database or some objects in the database.

ALTER, modify data definitions or properties, such as field type, size, and so on.

DROP, delete table structure and data attributes.

DCL: data control language

Commonly used statements such as GRANT,REVOKE,DENY are used to control the permissions of database users and roles.

GRANT, authorization

REVOKE, reclaim permissions

Summary: to put it simply, DML (data manipulation language) is a language for manipulating data content, and its minimum operating unit is rows.

DDL (data definition language) is a language for manipulating data objects and object properties. Its operations will change the table structure, table type and other data properties, but will not change the data content.

DCL (data control language) data control language, used to limit the permissions of database users.

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