参考博客:https://blog.csdn.net/tomatofly/article/details/5949070
DQL(data query language)
:数据查询语言
select
from
where
DML(data manipulation language)
:数据操纵语言
insert
update
delete
DDL(data definition language)
:数据定义语言,创建数据库、表、视图、索引
create
DCL(data control language)
:数据控制语言。授权
grant
rollback
commit