export and import dump file with constraints

if you are trying to import the dump file to db while the tables contain constraints,you may got following error information:

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IMP-00017: following statement failed with ORACLE error 942
“ALTER TABLE “R_MSGSTRUCT_RECIPIENT_DELIVINF” ADD CONSTRAINT “F1R_MSGSTRUCT_”
“RECI” FOREIGN KEY (“FK_MESSAGESTRUCT_ID”) REFERENCES “NC_MESSAGESTRUCT” (“P”
“K_MS_ID”) ENABLE NOVALIDATE”
IMP-00003: ORACLE error 942 encountered
ORA-00942: table or view does not exist
IMP-00017: following statement failed with ORACLE error 942
“ALTER TABLE “R_MSGSTRUCT_RECIPIENT_DELIVINF” ADD CONSTRAINT “F3R_MSGSTRUCT_”
“RECI” FOREIGN KEY (“FK_RECIPIENT_ID”) REFERENCES “NC_RECIPIENT” (“PK_RECIPI”
“ENT_ID”) ENABLE NOVALIDATE”
IMP-00003: ORACLE error 942 encountered
ORA-00942: table or view does not exist

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bad luck,maybe u need to manully resolve those problems.it seems exp has some limitations while handling the constraints