Oracle database language classification
a, DML (data manipulation language) data manipulation language: query, manipulate the data table data rows DML mainly used for data in the database of some operations.
select: searchable database table or view data
insert: add rows of data to a database table or view
update: Modify existing table or view rows of data
delete: delete a table or view existing data lines Note: DML statements are not It will automatically commit the transaction! Two, DDL (data definition language) database definition language: create, modify, delete data in the database table object DDL is mainly used in the definition or changing the structure of the table, the data type, the link between the tables and constraints initialization work.
create table: create table
alter table: Modify Table
drop table: drop table Note: DLL statement automatically commits the transaction! So DML statements can be rolled back before the transaction commits, the transaction can not be rolled back after the DDL statement is executed. Three, DCL (Data Control Language) database control language: grant permission for carrying out the operation to recover the DCL is used to set or change the database user or role privileges statements, including (grant, deny, revoke, etc.) statement.
grant: grant permissions to a user or role
revoke: all rights to recover user or role-
four, TCL (Transactional Control Language) language to control things: maintain data consistency
commit: Commits the database has been changed
rollback: rollback data has changed
save point: the point settings are saved for part of the data changes cancel
five, DQL (Data Query Language) database query languages:
including basic query, order by clause, group by clause and so on.