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+```mermaid
+sequenceDiagram
+    participant User
+    participant PaymentGateway
+    participant Database
+    opt Successful Transaction
+        User->>PaymentGateway: Initiate Payment
+        PaymentGateway-->>User: Payment Confirmation
+        User->>Database: Update Transaction Record
+        Database-->>User: Transaction Updated
+        User->>User: Payment Succeeded
+    end
+    opt External Failure
+        User->>PaymentGateway: Initiate Payment
+        PaymentGateway-->>User: Payment Error
+        User->>User: Payment Failed
+    end
+    opt DB Failure
+        User->>PaymentGateway: Initiate Payment
+        PaymentGateway-->>User: Payment Confirmation
+        User->>Database: Update Transaction Record
+        Database-->>User: DB Error
+        User->>PaymentGateway: Cancel Transaction
+        PaymentGateway-->>User: Transaction Canceled
+    end
+    %% Commit and Rollback%%
+    Note over User, PaymentGateway: Commit after successful transaction
+    Note over User, Database: Rollback on DB failure
+```
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