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Clarify aggregation challenge solution #382

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Clarify aggregation challenge solution #382

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366c258
Clarify aggregation challenge solution
Joe-Heffer-Shef Jan 10, 2025
af73a87
Update episodes/02-sql-aggregation.md
Joe-Heffer-Shef Jan 23, 2025
7ce4074
Update episodes/02-sql-aggregation.md
Joe-Heffer-Shef Jan 23, 2025
81295c0
Fix syntax for field name
Joe-Heffer-Shef Jan 23, 2025
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9 changes: 7 additions & 2 deletions episodes/02-sql-aggregation.md
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Expand Up @@ -226,11 +226,16 @@ Write a query that returns, from the `species` table, the number of

## Solution

This query counts the number of times each value (Bird, Rabbit, Reptile or Rodent) in the `taxa` field occurs, defining a new field named `taxa_count` to hold the result.
The `GROUP BY` clause means the query will create an aggregated table with one row for each taxa.
Only those `taxa` values that have more than ten records will be included because of the `HAVING` clause.
This filtering is applied _after_ grouping has been done.

```sql
SELECT taxa, COUNT(*) AS n
SELECT taxa, COUNT(*) AS taxa_count
FROM species
GROUP BY taxa
HAVING n > 10;
HAVING taxa_count > 10;
```

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