一，sql（Structure Query Language）语言分类

1，DDL(Data Description Language)数据描述语言

???? a.? create

????? b.? alert

????? c.?? drop

2，DCL(Data Control Language)数据控制语言

???? a.???grant

?????b.??? revoke

3，DML(Data Manipulation Language)数据操纵语言

???? a.?? select

???? b.?? delete

???? c.??? update

???? d.??? insert