SELECT   
(case when a.colorder=1 then d.name else '' end) as 表名,--如果表名相同就返回空   syscolumns(表字段信息表) a  sysobjects d
      a.colorder as 字段序号,  
      a.name as 字段名,  
      (case when COLUMNPROPERTY( a.id,a.name, 'IsIdentity' )=1 then '√' else '' end) as 标识,   --返回IsIdentity的值，IsIdentity只有两个值：0、1
      (case when (SELECT count(*) FROM sysobjects--查询主键  
                      WHERE (name in   
                              (SELECT name FROM sysindexes   
                              WHERE (id = a.id)   AND (indid in   
                                      (SELECT indid FROM sysindexkeys  
                                        WHERE (id = a.id) AND (colid in   
                                          (SELECT colid FROM syscolumns  
                                          WHERE (id = a.id) AND (name = a.name))  
                          )))))   
          AND (xtype = 'PK' ))>0 then '√' else '' end) as 主键,--查询主键END  
 b.name as 类型,   --systypes b
 a.length as 占用字节数,  
 COLUMNPROPERTY(a.id,a.name,'PRECISION' ) as    长度,  
 isnull(COLUMNPROPERTY(a.id,a.name,'Scale' ),0) as 小数位数,  
 (case when a.isnullable=1 then '√' else '' end) as 允许空,  
 isnull(e.text,'' ) as 默认值,   --syscomments e
 isnull(g.[value],'' ) AS 字段说明    --sys.extended_properties g (字段信息表)
 FROM syscolumns a left join systypes b   
 on a.xtype=b.xusertype  
 inner join sysobjects d   
 on a.id=d.id and d.xtype='U' and d.name 'dtproperties'   
 left join 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   
      where d.name='systempara' --所要查询的表  
 order by a.id,a.colorder  

select * from sys.extended_properties--字段信息表
select * from syscolumns--表字段信息表
select * from sysobjects where sysobjects.type='u'--数据库所有的用户创建的表的信息
select * from sysobjects where sysobjects.type='s'--数据库所有的系统表的信息
select * from syscomments --所有的触发器的东西
--COLUMNPROPERTY 返回有关列或过程参数的信息