SQLServer：
[sql] view plain copy
--获取所有非系统数据库 
select name from master..sysdatabases where name not in('master', 'model', 'msdb', 'tempdb', 'northwind', 'pubs', 'ReportServer', 'ReportServerTempDB') 
 
--获取某个表的详细字段信息 
select c.name,t.name,c.prec,p.value from syscolumns c 
inner join systypes t on c.xtype= t.xtype 
inner join sysobjects o on c.id= o.id 
inner join sys.extended_properties p  on c.id = p.major_id and c.colid = p.minor_id 
where  o.xtype='u'and t.status=0 and o.name='表名' 
 
 
--获取所有表信息 
select * from sysobjects where XType='U' 
 
--字段信息，关联表id=syscolumns.id 
select * from syscolumns  
 
--注释信息，关联字段信息major_id=syscolumns.id 
select * from sys.extended_properties 
 
--主键自增信息，关联id =syscolumns.id 
select * from sysindexkeys  
select * from sysindexes  
 
 
--表详细信息（字段名，类型，长度，是否是主键，是否是标识，允许空，注释） 
select a.name N'字段名', b.name N'类型',  
COLUMNPROPERTY(a.id,a.name,'PRECISION') as N'长度',  
(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 'PK' else '' end) N'主键',  
(case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then 'identity'else '' end) N'标识',  
(case when a.isnullable=1 then 'true'else 'false' end) N'允许空',  
isnull(g.[value],'') AS N'注释'  
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='表名' 
order by a.colorder 






oracle：
[sql] view plain copy
--获取当前用户所有的表 
SELECT *  FROM  user_tables 
 
--获取所有列，列信息 
SELECT * FROM user_tab_columns   
 
 
--2个视图中分别存储了当前用户的表信息 
--user_tab_columns：表中列的详情，但是没有是否是主键的标识 
--user_cons_columns：约束视图。 
SELECT utc.COLUMN_NAME as 列名,ucc.COLUMN_NAME AS 主键, utc.DATA_TYPE as 列类型,utc.DATA_LENGTH as 类型长度,utc.NULLABLE as 是否可为空 FROM user_tab_columns utc  
left join user_cons_columns ucc on utc.TABLE_NAME = ucc.TABLE_NAME   
where POSITION=1 AND ucc.TABLE_NAME ='你的表名'  
ORDER by utc.COLUMN_ID 
 
--user_col_comments：注释