查询表的基本信息

 -------------------------------------查询表的信息
 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='SystemNote' --所要查询的表   
 order by a.id,a.colorder 

 -------------字段信息表
 select * from sys.extended_properties
 -------------表字段信息表
select * from syscolumns
 -------------数据库所有的用户创建的表的信息
select * from sysobjects where sysobjects.type='u'
 -------------数据库所有的系统表的信息
select * from sysobjects where sysobjects.type='s'