https://www.cnblogs.com/w2011/archive/2013/01/04/2844143.html
SELECT 字段名= convert(varchar(100), a.name), 表名= convert(varchar(50), d.name ), 类型= CONVERT(varchar(50),b.name), 库名= 'ServerModeXpoDemo', 字段说明=convert(varchar(50), isnull(g.[value],'')) FROM dbo.syscolumns a left join dbo.systypes b on a.xusertype=b.xusertype inner join dbo.sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties' left join dbo.syscomments e on a.cdefault=e.id left join sys.extended_properties g on a.id=g.major_id and a.colid=g.minor_id left join sys.extended_properties f on d.id=f.major_id and f.minor_id=0 where d.name ='Car'
https://blog.csdn.net/xsjm206/article/details/6443590
1.select column_name,data_type,character_maximum_length
from information_schema.columns
where table_name='TableName' and column_name='ColName'
2.information_schema.columns是系统视图，记录表的字段的相关信息。
获取SQL Server数据库中的表和字段描述
https://www.cnblogs.com/billqian/p/5045164.html
获取所有dbo表的扩展属性：
SELECT * FROM fn_listextendedproperty (NULL, 'schema', 'dbo', 'table', default, NULL, NULL)
大概的结果：
objtype objname name value
TABLE 表名 扩展属性名 值
获取表的扩展属性：
select * from ::fn_listextendedproperty (null,'user','dbo','table','表名','column',null)
name=MS_Description 是系统提供的说明
获取字段属性，默认值等等：
SELECT * FROM INFORMATION_SCHEMA.COLUMNS
可以参考：http://www.cnblogs.com/chenxizhang/archive/2008/06/19/1225949.html