获取一个表的，字段，类型，长度，是否主键，是否为空，注释 等信息

（1）
SELECT 
表名=case when a.colorder=1 then d.name else '' end,
表说明=case when a.colorder=1 then isnull(f.value,'') else '' end,
字段序号=a.colorder,
字段名=a.name,
标识=case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end,
主键=case when exists(SELECT 1 FROM sysobjects where xtype='PK' and parent_obj=a.id and name in (
SELECT name FROM sysindexes WHERE indid in(
SELECT indid FROM sysindexkeys WHERE id = a.id AND colid=a.colid
))) then '√' else '' end,
类型=b.name,
占用字节数=a.length,
长度=COLUMNPROPERTY(a.id,a.name,'PRECISION'),
小数位数=isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0),
允许空=case when a.isnullable=1 then '√'else '' end,
默认值=isnull(e.text,''),
字段说明=isnull(g.[value],'')
FROM syscolumns a
left join systypes b on a.xusertype=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 sysproperties g on a.id=g.id and a.colid=g.smallid  
left join sysproperties f on d.id=f.id and f.smallid=0
--where d.name='要查询的表'    --如果只查询指定表,加上此条件
order by a.id,a.colorder

（2）

SQL2000系统表的应用 

1.查询数据库中的所有数据库名：

SELECT Name FROM Master..SysDatabases ORDER BY Name

2.查询某个数据库中所有的表名：

SELECT Name FROM SysObjects Where XType='U' ORDER BY Name

3.查询表结构信息：

SELECT (case when a.colorder=1 then d.name else null end) 表名,  
a.colorder 字段序号,a.name 字段名,
(case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 标识, 
(case when (SELECT count(*) FROM sysobjects  
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) 主键,b.name 类型,a.length 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) 允许空,  
isnull(e.text,'') 默认值,isnull(g.[value], ' ') AS [说明]
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
left join sys.extended_properties f on d.id=f.class and f.minor_id=0
where b.name is not null
--WHERE d.name='要查询的表' --如果只查询指定表,加上此条件
order by a.id,a.colorder

--1：获取当前数据库中的所有用户表

select Name from sysobjects where xtype='u' and status>=0

--2：获取某一个表的所有字段

select name from syscolumns where id=object_id('表名')

--3：查看与某一个表相关的视图、存储过程、函数

select a.* from sysobjects a, syscomments b where a.id = b.id and b.text like '%表名%'

--4：查看当前数据库中所有存储过程

select name as 存储过程名称 from sysobjects where xtype='P'

--5：查询用户创建的所有数据库

select * from master..sysdatabases D where sid not in(select sid from master..syslogins where name='sa')

或者

select dbid, name AS DB_NAME from master..sysdatabases where sid <> 0x01

--6：查询某一个表的字段和数据类型

select column_name,data_type from information_schema.columns
where table_name = '表名'

--7:取得表字段的描述
select name, 
(select value from sysproperties where id = syscolumns.id and smallid=syscolumns.colid) as 描述
from syscolumns where id=object_id('表名')