﻿ SQL: Find the average purchase amount of all orders

# SQL Exercises: Find the average purchase amount of all orders

## SQL Aggregate Functions: Exercise-2 with Solution

From the following table, write a SQL query to calculate the average purchase amount of all orders. Return average purchase amount.

Sample table: orders

Sample Solution:

``````SELECT AVG (purch_amt)
FROM orders;``````

Output of the Query:

```avg
1461.7650000000000000
```

Code Explanation:

The said SQL query retrieves the average of values in the "purch_amt" column from the 'orders' table. The "SELECT AVG (purch_amt)" statement specifies that the average of the values in the "purch_amt" column should be retrieved. The result of this query will be a single value that represents the average of all values in the "purch_amt" column in the 'orders' table.

Relational Algebra Expression:

Relational Algebra Tree:

Explanation:

visual presentation :

## Query Visualization:

Duration:

Rows:

Cost:

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Previous SQL Exercise: Find the total purchase amount for all orders.
Next SQL Exercise: Find the number of salesmen for each customer.

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## SQL: Tips of the Day

What is the best way to paginate results in SQL Server?

```SELECT  *
FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY OrderDate ) AS RowNum, *
FROM      Orders
WHERE     OrderDate >= '1980-01-01'
) AS RowConstrainedResult
WHERE   RowNum >= 1
AND RowNum < 20
ORDER BY RowNum
```

Database: SQL Server

Ref: https://bit.ly/3MGrNlk

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