when I try to change from AL16UTF16 default setting to UTF8 got the error ORA-12717: Cannot issue ALTER DATABASE NATIONAL CHARACTER SET when NCLOB, NCHAR or NVARCHAR2 data exists
but looking for columns having the NCLOB or NVARCHAR2 only 7 tables in XDB schema, and no data at all.
I attempted to modify the XDB tables column from NVARCHAR2 to varchar2 (temporary then change back if succeeded to UTF8), it says tables not found. I assume it was because it is oracle managed schema. So any advice how to change to UTF8?
select * from sdb.JSON$COLLECTION_METADATA;
select * from xdb.xdb$Xtab;
select * from xdb.XDB$XTABNMSP;
select * from xdb.XDB$XTABCOLS;
select * from xdb.JSON$COLLECTION_METADATA_V;
select * from xdb.JSON$USER_COLLECTION_METADATA;