1、先关掉所有外键约束：

SELECT ‘alter table  ‘|| t.table_name || ‘ disable constraint ‘ || t.CONSTRAINT_NAME || ‘;‘
FROM USER_CONSTRAINTS t WHERE t.CONSTRAINT_TYPE = ‘R‘;
 
2、导入dmp文件

3、开启所有外键约束：
SELECT ‘alter table  ‘|| t.table_name || ‘ enable constraint ‘ || t.CONSTRAINT_NAME || ‘;‘
FROM USER_CONSTRAINTS t WHERE t.CONSTRAINT_TYPE = ‘R‘;