Banner With the Best Click-Through

Problem

Table: `BannerLog`

```text
+-----------+---------+
| Column | Type |
+-----------+---------+
| event_ref | int |
| event_type| varchar |
| banner_id | int |
+-----------+---------+
Each row is an event for a banner. `event_type` is either 'impression' (the banner was shown) or 'click' (a user clicked it).
```

Report the `banner_id` with the highest **click-through rate**, where click-through rate = (number of 'click' rows) / (number of 'impression' rows) for that banner. If several banners tie on the highest rate, report the one with the smallest `banner_id`. Label the output column `top_banner`.

Tables

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 1 row with the columns top_banner.

Starter code (SQL)

SELECT *
FROM BannerLog;

Related SQL questions

• 3-Day Tweet Rolling AverageMedium
• 7-Day vs 28-Day Rolling Avg DivergenceMedium
• A/B Test Sample Ratio Mismatch (SRM) CheckMedium
• Accounts Streaming From Two Devices at OnceMedium
• Ad Campaign Funnel AnalysisMedium
• Agent Resolution RateMedium