# Subquery
## Definition(s)
### Context: [[Nexus - Google Analytics Certificate Course#5.3 Google Analytics - 5 Analyze - Module 3 - Aggregate Data for Analysis Aggregate Data for Analysis|Google Analytics Certificate]]
#### Sub-context: [[Query]]
>[! Definition]
>A subquery is a query within a query.
## Examples
```sql
SELECT
account_table.*
FROM (
SELECT *
FROM transaction.sf_model_feature_2014_01
WHERE day_of_week = 'Friday'
) AS account_table
WHERE
account_table.availability = 'YES'
```
- For a subquery to compare multiple columns, those columns must be selected in the main query.
## Related
## Resources
[SQL subqueries tutorial](https://www.w3resource.com/sql/subqueries/understanding-sql-subqueries.php)
[Subquery practice tutorial and problems](https://mode.com/sql-tutorial/sql-sub-queries/)
## Flashcards
The below code are generated for use with [Spaced Repetition plugin](https://github.com/st3v3nmw/obsidian-spaced-repetition/) [docs](https://www.stephenmwangi.com/obsidian-spaced-repetition/)