Suppose, you have a table and you want to compute the **average value for all the rows** in a table or for some **subset of rows**. For example, you would like to compute the **average LifeExpectancy **of humans across all countries or may be you would like to compute the ** average LifeExpectancy** by

**Continent**

.### Solution –

If you want to calculate the average value of a column, you can simply apply the **AVG() function** to that column.

```
SELECT
AVG(LifeExpectancy) as avg_life_expectancy
FROM
country
```

To calculate the average life expectancy by continent, we have to first group the data by Continent using the **GROUP BY** then apply the **AVG() function** to the LifeExpectancy column.

```
SELECT
Continent,
AVG(LifeExpectancy) as avg_life_expectancy
FROM
country
GROUP BY
Continent
```

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