Practice IBM SQL Question | Real Coding Interviews

Quick Summary

Calculate the average elapsed time between ticket creation and resolution in hours.
Exclude unresolved tickets and handle empty datasets by returning null.
Format the final average to exactly two decimal places with trailing zeros.

What This Tests

Filtering based on NULL conditions before aggregation
Computing time deltas and converting units
Handling aggregate functions over empty result sets
Formatting numeric output to fixed precision

Common Patterns

Aggregation

Date Arithmetic

Table: support_tickets

+-------------+-------------+
| Column Name | Type        |
+-------------+-------------+
| id          | INT         |
| customer_id | INT         |
| created_at  | VARCHAR(19) |
| resolved_at | VARCHAR(19) |
+-------------+-------------+

Each row represents a support ticket and its creation and resolution times.

Test Cases

Input

Output

Expected