Resolution record (4)-Oracle not support parallel transaction

[Problem description]
The prompt "Oracle not support parallel transaction" is displayed when you call Dal to execute the stored procedure and write data to the database"

[Error cause]
1. When a transaction does not end and starts another transaction.
2. There are nested subtransactions.
3. Started distributed transactions and started a local transaction.

In msdn, oledb supports nested transactions, but it does not work in Oracle.

[Solution]
1. Close the connection as soon as possible.
2. Control the transaction and avoid the third error.
3. Do not start nested transactions when using oledb.