【AntDB数据库 SQL语法专栏】——DDL语句（5）

DROP SCHEMA

说明：

移除一个模式

语法：

DROP SCHEMA [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]

示例：

--从数据库中移除模式mystuff及其中 所包含的对象：
DROP SCHEMA mystuff CASCADE;

CREATE USER

说明：

定义一个新的数据库角色

语法：

CREATE USER name [ [ WITH ] option [ ... ] ]

这里 option 可以是：

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'
    | IN ROLE role_name [, ...]
    | IN GROUP role_name [, ...]
    | ROLE role_name [, ...]
    | ADMIN role_name [, ...]
    | USER role_name [, ...]
    | SYSID uid

示例：

--创建一个超级用户，并赋予登录权限
CREATE USER user1 SUPERUSER PASSWORD '123456' LOGIN;

ALTER USER

说明：

更改一个数据库角色

语法：

ALTER USER role_specification [ WITH ] option [ ... ]

其中 option 可以是：

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'

ALTER USER name RENAME TO new_name

ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter { TO | = } { value | DEFAULT }
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] SET configuration_parameter FROM CURRENT
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] RESET configuration_parameter
ALTER USER { role_specification | ALL } [ IN DATABASE database_name ] RESET ALL

其中 role_specification 可以是：

    role_name
  | CURRENT_USER
  | SESSION_USER

示例：

--重命名用户
ALTER USER adb01 RENAME TO adb02;

DROP USER

说明：

移除一个数据库角色

语法：

DROP USER [ IF EXISTS ] name [, ...]

示例：

--移除用户adb01:
DROP USER IF EXISTS adb01;

CREATE ROLE

说明：

定义一个新的数据库角色

语法：

CREATE ROLE name [ [ WITH ] option [ ... ] ]

where option可以是：

      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | REPLICATION | NOREPLICATION
    | BYPASSRLS | NOBYPASSRLS
    | CONNECTION LIMIT connlimit
    | [ ENCRYPTED ] PASSWORD 'password' | PASSWORD NULL
    | VALID UNTIL 'timestamp'
    | IN ROLE role_name [, ...]
    | IN GROUP role_name [, ...]
    | ROLE role_name [, ...]
    | ADMIN role_name [, ...]
    | USER role_name [, ...]
    | SYSID uid

示例：

--创建一个能登录但是没有口令的角色：
CREATE ROLE jonathan LOGIN;

--创建一个有口令的角色：
CREATE USER davide WITH PASSWORD 'jw8s0F4';