master数据库里的哪个表存储了用户表的数据结构

sysobjects 存储的是表和各种对象信息。
syscolumns 存储的是字段信息。
两个表联合就能得到表结构信息了。

select a.name,b.name, a.*,b.* from sysobjects a , syscolumns b
where a.type = 'u'
and a.id = b.id
order by a.id , b.colid

表名:sysobjects

例:
SELECT CASE WHEN a.colorder = 1 THEN d.name ELSE '' END AS 表名,
CASE WHEN a.colorder = 1 THEN isnull(f.value, '') ELSE '' END AS 表说明,
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,
CASE WHEN EXISTS
(SELECT 1
FROM sysobjects
WHERE xtype = 'PK' AND name IN
(SELECT name
FROM sysindexes
WHERE indid IN
(SELECT indid
FROM sysindexkeys
WHERE id