如何将多个表空间的数据导入到单个表空间(USER_A到USER_B)

1.USER_A的数据保存在多个表空间中，首先导出USER_A的数据：
           exp file=USER_A_BAK.dmp  log=exp_USER_A.log
        2.创建用户USER_B:
       
           create user USER_B
           identified by "USER_B"
           default tablespace USER_B_DEFAULT_TABLESPACE
           temporary tablespace TEMP
           profile DEFAULT
           quota unlimited on USER_B_DEFAULT_TABLESPACE;
         
           grant connect to USER_B with admin option;
           --grant dba to USER_B with admin option;
           --grant resource to USER_B;
           grant create any table to USER_B with admin option;
           grant delete any table to USER_B with admin option;
           grant insert any table to USER_B with admin option;
           grant select any table to USER_B with admin option;
           --grant unlimited tablespace to USER_B with admin option;
           grant update any table to USER_B with admin option;
          
     3.导入数据到USER_B:
    
         imp file=USER_A_BAK.dmp fromuser=USER_A touser=USER_B log=imp_USER_B.log
        
     4.注意点：
    
         --前面不能授予这些权限(在第二步已经注释)，导完后授权
        grant dba to USER_B with admin option;
        grant resource to USER_B;
        grant unlimited tablespace to USER_B with admin option;