Concepts and differences of DQL, DML, DDL, DCL

SQL language is divided into four categories: data Query Language DQL, Data manipulation language DML, data definition language DDL, Data Control Language DCL data Query Language DQL
Data Query Language DQL The basic structure is the SELECT clause, the FROM clause, where
A query block consisting of a clause:
SELECT < field Name table >
From < table or view name >
WHERE < query conditions > Data Manipulation language DML
Data manipulation language DML mainly has three kinds of forms:
1) Inserting: Insert
2) Updated: Update
3) Delete: Delete data definition language DDL
Data definition Language DDL is used to create various objects in a database-– tables, views,
indexes, synonyms, clusters, etc. such as:
CREATE table/view/index/syn/cluster (tables, views, indexes, synonyms, clusters)
DDL operations are implicitly committed. Cannot rollback Data Control Language DCL
The Data Control Language DCL is used to grant or reclaim certain privileges to access the database and to control
The database manipulates the time and effect that the transaction takes place, monitors the database and so on. Such as:
1 Grant: Authorization.
2) ROLLBACK: Back to a certain point.
3) Commit: Submit.