SQL CROSS JOIN
Every row from one table paired with every row from the other — no matching condition at all, deliberately.
What & Why
CROSS JOIN produces every possible combination of its two inputs, with no ON condition. Pairing every marketing.campaigns row with every distinct lead country creates a complete campaign-by-market planning grid, and its row count is the two input counts multiplied together.
See How It Works
Marketing wants a planning grid containing every campaign and every country currently represented by its leads.
| id | name | channel | spend | start_date | end_date | status | target_segment |
|---|---|---|---|---|---|---|---|
| 1 | Spring Launch | google_ads | 55000.00 | 2024-01-15 | 2024-03-31 | active | smb |
| 2 | Retention Webinar | 45000.00 | 2024-02-10 | 2024-04-15 | active | enterprise | |
| 3 | Finance Retargeting | 50000.00 | 2024-03-12 | 2024-05-31 | active | enterprise | |
| 4 | Enterprise Search | google_ads | 60000.00 | 2024-04-01 | 2024-06-30 | active | enterprise |
| id | campaign_id | created_at | qualified_at | converted_at | lead_score | source | country | |
|---|---|---|---|---|---|---|---|---|
| 301 | 1 | ana@example.com | 2024-01-21 09:10:00+00 | 2024-01-22 11:00:00+00 | 2024-02-02 10:00:00+00 | 86 | google_ads | US |
| 302 | 1 | ben@example.com | 2024-01-24 12:40:00+00 | NULL | NULL | 52 | google_ads | CA |
| 303 | 2 | chloe@example.com | 2024-02-16 08:30:00+00 | 2024-02-18 14:20:00+00 | NULL | 74 | GB | |
| 304 | 3 | dev@example.com | 2024-03-20 17:15:00+00 | 2024-03-21 09:00:00+00 | 2024-04-04 16:00:00+00 | 91 | US |
| id | name |
|---|---|
| 1 | Spring Launch |
| 2 | Retention Webinar |
| 3 | Finance Retargeting |
| 4 | Enterprise Search |
| country |
|---|
| CA |
| GB |
| US |
| campaign_name | country |
|---|---|
| Enterprise Search | CA |
Enterprise Search and CA become one result row. Four campaigns × three stored countries produces twelve rows.
SELECT
c.name AS campaign_name,
markets.country
FROM marketing.campaigns c
CROSS JOIN (
SELECT DISTINCT country
FROM marketing.leads
WHERE country IS NOT NULL
) markets
ORDER BY campaign_name, country;Practice this concept
Marketing wants every campaign paired with every country represented by its leads.
marketingPrefix tables with marketing.table_name.
campaign_namecountrymarketing.campaigns| Column | Type |
|---|---|
| id | integer |
| name | text |
| channel | text |
| spend | numeric |
| start_date | date |
| end_date | date |
| status | text |
| target_segment | text |
| legacy_id | text |
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