取得Ms SqlServer数据库中某张表的所有列：
SELECT sysobjects.name AS TABLENAME,
syscolumns.NAME as NAME,
systypes.name VTYPE,
syscolumns.LENGTH,
syscolumns.XPREC,
syscolumns.XSCALE,
isnullable,
cdefault
FROM syscolumns,sysobjects,systypes
WHERE syscolumns.id = sysobjects.id and
syscolumns.xtype = systypes.xtype and
sysobjects.type='U' and
sysobjects.name = 表名
取得Oracle数据库某张表的所有列:
SELECT TNAME AS TABLENAME,
CNAME AS NAME,
COLTYPE AS VTYPE,
WIDTH AS LENGTH,
PRECISION AS XPREC,
SCALE AS XSCALE,
NULLS AS isnullable,
DEFAULTVAL AS cdefault
FROM COL
WHERE TNAME = 表名;
取得Ms Sqlserver数据库的所有外键信息
select
b.name as key_name,
a.name as name,
d.name as f_name
from sysobjects a join sysobjects b on a.id=b.parent_obj
join sysforeignkeys c on b.id=c.constid
join sysobjects d on c.rkeyid=d.id
join sysindexkeys e on d.id=e.id
join syscolumns f on a.id=f.id and e.colid=f.colid
where b.xtype='F'
取得Oracle数据库的所有外键信息：
select all_constraints.constraint_name as key_name,
all_constraints.table_name as name ,
all_indexes.table_name as f_name
from all_constraints,all_indexes
where constraint_name like 'FK%'
and all_constraints.r_constraint_name = all_indexes.index_name