1.查詢資料庫中的所有資料庫名：
 SELECT Name FROM Master..SysDatabases ORDER BY Name
 2.查詢某個資料庫中所有的表名：
 SELECT Name FROM SysObjects Where XType='U' ORDER BY Name
 
 
 3.查詢表結構資訊：
 SELECT (case when a.colorder=1 then d.name else null end) 表名,  
a.colorder 欄位序號,a.name 欄位名,
(case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 標識, 
(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) 主鍵,b.name 型別,a.length 佔用位元組數,  
COLUMNPROPERTY(a.id,a.name,'PRECISION') as 長度,  
isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as 小數位數,(case when a.isnullable=1 then '√'else '' end) 允許空,  
isnull(e.text,'') 預設值,isnull(g.[value], ' ') AS [說明]
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='要查詢的表' --如果只查詢指定表,加上此條件
order by a.id,a.colorder