Write a SQL query to find the second-highest margin call amount from a transactions database.
Use the transactions table and treat duplicate margin call amounts as one value. Exclude non-margin-call transactions and rows where the amount is missing.
second_highest_margin_call_amount.| Column | Type | Description |
|---|---|---|
| transaction_idPK | INT | Unique transaction identifier |
| transaction_type | VARCHAR(30) | Transaction classification |
| amount | DECIMAL(12,2) | Margin call or transaction amount |
| transaction_date | DATE | Date the transaction was recorded |