sql语言改数据库空间大小

sql语言怎么改数据库空间使用大小和日志空间大小
例如原来的的数据库空间大小是100MB怎么改成800MB 还有日志是100变成800MB
用SQL语句
我的数据库名是jiushishujuku要怎么操作，给个实例

alter database jiushishujuku
add file
(
name=dbfile2,
filename="d:\jdata2.ndf"
maxsize=600
)

--再加log
alter database jiushishujuku
add log file
(
name=dbjlogfile2,
filename="d:\jlog2.ndf"
maxsize=100
)

ALTER DATABASE database
{ ADD FILE < filespec > [ ,...n ] [ TO FILEGROUP filegroup_name ]
| ADD LOG FILE < filespec > [ ,...n ]
| REMOVE FILE logical_file_name
| ADD FILEGROUP filegroup_name
| REMOVE FILEGROUP filegroup_name
| MODIFY FILE < filespec >
| MODIFY NAME = new_dbname
| MODIFY FILEGROUP filegroup_name {filegroup_property | NAME = new_filegroup_name }
| SET < optionspec > [ ,...n ] [ WITH < termination > ]
| COLLATE < collation_name >
}

ALTER DATABASE .... MAXSIZE=800 MB