Two Methods for connecting oledb to Oracle

This is also an old problem. Simply write it here, so that the next time you encounter it, you will not be overwhelmed by headless flies.
You can use oledb to connect to an Oracle database. Generally, there are two kinds of providers.
A: provider = msdaora.1
B: provider = oraoledb. Oracle
The first is Microsoft's Oracle component, and the second is the Oracle access component.
Two character sets frequently used by Oracle databases
C: English: Simplified chinese_china.us7ascii
D: Chinese: Simplified chinese_china.zhs16gbk
When a works with C and D, Data Reading and Writing is free of garbled characters. If garbled characters occur, modify the environment variable nls_lang at the system level (non-user level) to the character set used by the database and restart the computer.
Disadvantage: Long, clob, and BLOB fields are not supported.
B supports big fields and works perfectly with D. If BC is used in combination, the system reads no garbled characters and writes the data to garbled characters. The Chinese parameter passed as the where condition is garbled. Unavailable. If the database character set is C, only a can be used. To read large fields, you must use B to create a new connection.