Explain what a transaction is and why it matters in a system that processes concurrent requests.
Using the transaction and request-operation records, write a SQL query that produces a concise summary for each recorded transaction. Include transactions with no recorded requests. Requests without a matching transaction should not appear in any transaction summary.
transaction_id, isolation_level, status, request_count, failed_request_count, and duration_ms.200, including NULL, as failed.duration_ms descending, then transaction_id ascending.| Column | Type | Description |
|---|---|---|
| transaction_idPK | INT | Unique database transaction identifier |
| isolation_level | VARCHAR(30) | Isolation level used by the transaction |
| status | VARCHAR(30) | Final transaction status |
| started_at | TIMESTAMP | Transaction start timestamp |
| ended_at | TIMESTAMP | Transaction completion timestamp |
| Column | Type | Description |
|---|---|---|
| request_idPK | INT | Unique request identifier |
| transaction_id | INT | Associated database transaction identifier |
| operation | VARCHAR(30) | Operation performed by the request |
| response_status | VARCHAR(50) | Response status returned by the operation |