为A用户赋给B用户表的权限

grant select 用户B.表名 to 用户A

查询主表与引用表之间的关系

select a.owner as 主键拥有者,a.table_name as 主键表,--
        b.column_name as 主键列,--
        c.OWNER as 外键拥有者,-- 
        c.table_name as 外键表,--
        d.column_name as  外键列 -- 
 from user_constraints  a  
 left join user_cons_columns b   
             on a.constraint_name=b.constraint_name 
 left join user_constraints c   
             on c.R_CONSTRAINT_NAME=a.constraint_name 
 left join user_cons_columns d  
             on c.constraint_name=d.constraint_name 
 where  a.constraint_type='P'  
 order by a.table_name

* 禁用试图 *

alter table 表名 disable constraint 约束名;

select 'alter table '||table_name||' disable constraint '||constraint_name||';' from user_constraints where constraint_type='R' select 'alter table '||table_name||' enable constraint '||constraint_name||';' from user_constraints where constraint_type='R'

查询并导入空表

select table_name from user_tables where NUM_ROWS=0;  
 select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0 ;