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# Revising Aggregations - The Sum Function

[Question Link](https://www.hackerrank.com/challenges/revising-aggregations-sum/problem?isFullScreen=true)

Query the total population of all cities in **CITY** where *District* is **California**. 

**Input Format**

The **CITY** table is described as follows:

![](https://s3.amazonaws.com/hr-challenge-images/8137/1449729804-f21d187d0f-CITY.jpg)

```sql
SELECT SUM(population)
FROM City
WHERE district = 'California'
```