You are given a single table of PNC deposit transactions. Write a SQL query to return the top 3 customers by total posted deposit amount. Only include rows where transaction_type = 'Deposit' and status = 'Posted'. The result should show each customer's name and total deposited amount, sorted from highest to lowest total.
| Column | Type | Description |
|---|---|---|
| transaction_idPK | INT | Unique transaction identifier |
| customer_name | VARCHAR(100) | Customer full name |
| branch_name | VARCHAR(100) | PNC branch where the transaction was recorded |
| transaction_type | VARCHAR(20) | Transaction type such as Deposit or Withdrawal |
| status | VARCHAR(20) | Transaction status such as Posted, Pending, or Reversed |
| amount | DECIMAL(12,2) | Transaction amount |
| transaction_date | DATE | Date the transaction occurred |