ORA-02293: cannot validate (SQL_NULQMYGZSKRAUDHWIMYONNRHI.TRN_CHK) - check constraint violated code example

Example: ORA-02293: unable to validate (GREENMILE.CK_FIELD01) - check constraint violated

ALTER TABLE suppliers
ADD CONSTRAINT check_supplier_name
  CHECK (supplier_name IN ('IBM', 'Microsoft', 'NVIDIA'));