关于Oracle与SqlServer中获取所有字段、主键、外键的sql语句

关于Oracle与SqlServer中获取所有字段、主键、外键的sql语句 标签： 主键  外键  sql 
最近在做的社会网络分析原型系统需要将多种不同数据库中的表的字段、主外键信息读出，实现这些功能费了不少功夫，记录下来以备用吧
Oracle:
查询某个表中的字段名称、类型、精度、长度、是否为空
select COLUMN_NAME,DATA_TYPE,DATA_PRECISION,DATA_SCALE,NULLABLE
from user_tab_columns
where table_name ='YourTableName'
查询某个表中的主键字段名
select col.column_name
from user_constraints con,  user_cons_columns col
where con.constraint_name = col.constraint_name
and con.constraint_type='P'
and col.table_name = 'YourTableName'
查询某个表中的外键字段名称、所引用表名、所应用字段名
select distinct(col.column_name),r.table_name,r.column_name
from
user_constraints con,
user_cons_columns col,
(select t2.table_name,t2.column_name,t1.r_constraint_name
 from user_constraints t1,user_cons_columns t2
 where t1.r_constraint_name=t2.constraint_name
 and t1.table_name='YourTableName'
 ) r
where con.constraint_name=col.constraint_name
and con.r_constraint_name=r.r_constraint_name
and con.table_name='YourTableName'

SQLServer中的实现：
字段：
SELECT c.name,t.name,c.xprec,c.xscale,c.isnullable
FROM systypes t,syscolumns c
WHERE t.xtype=c.xtype
AND c.id = (SELECT id FROM sysobjects WHERE name='YourTableName')
ORDER BY c.colid

主键（参考SqlServer系统存储过程sp_pkeys）：
select COLUMN_NAME = convert(sysname,c.name)              
from                                                      
sysindexes i, syscolumns c, sysobjects o                  
where o.id = object_id('[YourTableName]')                 
and o.id = c.id                                           
and o.id = i.id                                           
and (i.status & 0x800) = 0x800                            
and (c.name = index_col ('[YourTableName]', i.indid,  1) or    
     c.name = index_col ('[YourTableName]', i.indid,  2) or    
     c.name = index_col ('[YourTableName]', i.indid,  3) or    
     c.name = index_col ('[YourTableName]', i.indid,  4) or    
     c.name = index_col ('[YourTableName]', i.indid,  5) or    
     c.name = index_col ('[YourTableName]', i.indid,  6) or    
     c.name = index_col ('[YourTableName]', i.indid,  7) or    
     c.name = index_col ('[YourTableName]', i.indid,  8) or    
     c.name = index_col ('[YourTableName]', i.indid,  9) or    
     c.name = index_col ('[YourTableName]', i.indid, 10) or    
     c.name = index_col ('[YourTableName]', i.indid, 11) or    
     c.name = index_col ('[YourTableName]', i.indid, 12) or    
     c.name = index_col ('[YourTableName]', i.indid, 13) or    
     c.name = index_col ('[YourTableName]', i.indid, 14) or    
     c.name = index_col ('[YourTableName]', i.indid, 15) or    
     c.name = index_col ('[YourTableName]', i.indid, 16)      
     )

外键：
select t1.name,t2.rtableName,t2.name
from
(select col.name, f.constid as temp
 from syscolumns col,sysforeignkeys f
 where f.fkeyid=col.id
 and f.fkey=col.colid
 and f.constid in
 ( select distinct(id) 
   from sysobjects
   where OBJECT_NAME(parent_obj)='YourTableName'
   and xtype='F'
  )
 ) as t1 ,
(select OBJECT_NAME(f.rkeyid) as rtableName,col.name, f.constid as temp
 from syscolumns col,sysforeignkeys f
 where f.rkeyid=col.id
 and f.rkey=col.colid
 and f.constid in
 ( select distinct(id)
   from sysobjects
   where OBJECT_NAME(parent_obj)='YourTableName'
   and xtype='F'
 )
) as t2
where t1.temp=t2.temp