SQL Exercises: Find the largest number of orders booked by the customer

SQL Formatting Output: Exercise-9 with Solution

From the following table, write a SQL query that counts the unique orders and the highest purchase amount for each customer. Sort the result-set in descending order on 2nd field. Return customer ID, number of distinct orders and highest purchase amount by each customer.

Sample table: orders

Sample Solution:

SELECT customer_id, COUNT(DISTINCT ord_no), 
MAX(purch_amt) 
FROM orders 
GROUP BY customer_id 
ORDER BY 2 DESC;

Output of the Query:

customer_id	count		max
3002		3		5760.00
3009		2		2480.40
3005		2		948.50
3004		1		1983.43
3001		1		270.65
3007		1		2400.60
3008		1		250.45
3003		1		75.29

Relational Algebra Expression:

Relational Algebra Tree:

Explanation:

Pictorial presentation:

Practice Online

Query Visualization:

Duration:

Rows:

Cost:

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Previous: From the following table, write a SQL query to find all the customers. Sort the result-set in descending order on 3rd field. Return customer name, city and grade.
Next: From the following table, write a SQL query to calculate summation of purchase amount, total commission (15% for all salesmen) by each order date. Sort the result-set on order date. Return order date, summation of purchase amount and commission.