What are the Transaction levels available?
| Isolation Level | Transactions | Dirty Reads | Non-Repeatable Reads | Phantom Reads | | TRANSACTION_NONE | Not supported | Not applicable | Not applicable | Not applicable |
| TRANSACTION_READ_COMMITTED | Supported | Prevented | Allowed | Allowed |
| TRANSACTION_READ_UNCOMMITTED | Supported | Allowed | Allowed | Allowed |
| TRANSACTION_REPEATABLE_READ | Supported | Prevented | Prevented | Allowed |
| TRANSACTION_SERIALIZABLE | Supported | Prevented | Prevented | Prevented |
- A
non-repeatable read occurs when transaction A retrieves a row, transaction B subsequently updates the row, and transaction A later retrieves the same row again. Transaction A retrieves the same row twice but sees different data.
- A
phantom read occurs when transaction A retrieves a set of rows satisfying a given condition, transaction B subsequently inserts or updates a row such that the row now meets the condition in transaction A, and transaction A later repeats the conditional retrieval. Transaction A now sees an additional row. This row is referred to as a phantom.
