SQL AVG Operator Explained – Solve Intermediate SQL Questions Easily
Understanding the Orders Table
Before diving into SQL queries, let’s take a closer look at the structure of the orders table we will be working with. The table contains the following columns:
- Order ID
- Order Date
- Order Amount
- Customer ID
- Order Status
- Shipping Address
Key Data Points
The primary focus of our SQL query will be to retrieve:
- The year of the order date
- The average order amount for each year
Writing the SQL Query
To answer the question effectively, we need to construct an SQL query that retrieves the year from the order date and calculates the average order amount. Here’s how to do it step by step.
Step 1: Selecting the Year from Order Date
In SQL, we can use the YEAR() function to extract the year from the order date. Here’s the syntax we will use:
SELECT YEAR(order_date) AS order_year
Step 2: Calculating the Average Order Amount
Next, we need to calculate the average order amount using the AVG() function. The SQL syntax for this part will look like:
AVG(order_amount) AS average_order_amount
Step 3: Grouping the Results
To ensure we get the average order amount for each year, we will use the GROUP BY clause. This will allow us to group the results by the order year:
GROUP BY YEAR(order_date)
Step 4: Ordering the Results
Finally, we need to display the results in chronological order. Since SQL defaults to ascending order, we can simply use the ORDER BY clause:
ORDER BY order_year
Complete SQL Query
Putting it all together, the complete SQL query will look like this:
SELECT
YEAR(order_date) AS order_year,
AVG(order_amount) AS average_order_amount
FROM
orders
GROUP BY
YEAR(order_date)
ORDER BY
order_year;
Conclusion
By following these steps, you can effectively answer intermediate SQL questions involving the AVG operator. Understanding how to manipulate and analyze data using SQL is a vital skill for any data engineer. Practice this query with your own datasets to enhance your SQL proficiency and prepare for real-world data challenges. Happy querying!
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