1.oracle查询所有当前数据库的表语句：
select 'drop table '||table_name||';' as sqlscript from user_tables;
2.sql查询所有当前数据库的表语句：
//查询用户下所有数据库
SELECT Name FROM Master..SysDatabases ORDER BY Name
//查询某数据库下所有表
SELECT 'drop tbale'+' '+ Name FROM SysObjects Where XType='U' ORDER BY Name
//查询表结构信息
SELECT (case when a.colorder=1 then d.name else null end) 表名,
a.colorder 字段序号,a.name 字段名,
(case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 标识,
(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) 主键,b.name 类型,a.length 占用字节数,
COLUMNPROPERTY(a.id,a.name,'PRECISION') as 长度,
isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as 小数位数,(case when a.isnullable=1 then '√'else '' end) 允许空,
isnull(e.text,'') 默认值,isnull(g.[value], ' ') AS [说明]
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='要查询的表' --如果只查询指定表,加上此条件
order by a.id,a.colorder
3.有关数据库分离的一些小知识点
（1）数据库分离之前先检查分离数据库的大小、属性、缓存设置及存放位置；
（2）数据库分离时如果连接数大于0，需要清空连接数；
（3）数据库分离后就可以进行复制、粘贴；
（4）分离后的数据库如果用需要附加后才能使用；