Oracle modify the database character set

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first time I encountered this problem was that when I was migrating the database, I encountered different encodings of the two databases, and reported the ORA-02374 ORA-12899 ORA-02372 error when importing impdp.
Examples of errors:

ORA-02374: conversion error loading table "QBJMES"."PROJECT"
ORA-12899: value too large for column PROJECT_SPEC (actual: 103, maximum: 100)
ORA-02372: data for row: PROJECT_SPEC : 0X'3730B6A1BCB6302E382A302E362A323035302A39363028312E'

SQL>SHUTDOWN IMMEDIATE;

SQL>STARTUP MOUNT EXCLUSIVE;

SQL>ALTER SYSTEM ENABLE RESTRICTED SESSION;

SQL>ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;

SQL>ALTER SYSTEM SET AQ_TM_PROCESSES=0;

SQL>ALTER DATABASE OPEN;

SQL>ALTER DATABASE NATIONAL CHARACTER SET INTERNAL_USE UTF8;

SQL>SHUTDOWN immediate;

SQL>startup;

If it is gbk, it is ZHS16GBK

In the penultimate sentence, use the following to
ALTER DATABASE character set INTERNAL_USE ZHS16GBK;