SQL Exercises: Find salesman commission details of given customer

SQL Query on Multiple Tables: Exercise-7 with Solution

From the following tables, write a SQL query to find all orders executed by the salesperson and ordered by the customer whose grade is greater than or equal to 200. Compute purch_amt*commission as “Commission”. Return customer name, commission as “Commission%” and Commission.

Sample table: salesman

 salesman_id |    name    |   city   | commission 
-------------+------------+----------+------------
        5001 | James Hoog | New York |       0.15
        5002 | Nail Knite | Paris    |       0.13
        5005 | Pit Alex   | London   |       0.11
        5006 | Mc Lyon    | Paris    |       0.14
        5007 | Paul Adam  | Rome     |       0.13
        5003 | Lauson Hen | San Jose |       0.12

Sample table: customer

 customer_id |   cust_name    |    city    | grade | salesman_id 
-------------+----------------+------------+-------+-------------
        3002 | Nick Rimando   | New York   |   100 |        5001
        3007 | Brad Davis     | New York   |   200 |        5001
        3005 | Graham Zusi    | California |   200 |        5002
        3008 | Julian Green   | London     |   300 |        5002
        3004 | Fabian Johnson | Paris      |   300 |        5006
        3009 | Geoff Cameron  | Berlin     |   100 |        5003
        3003 | Jozy Altidor   | Moscow     |   200 |        5007
        3001 | Brad Guzan     | London     |       |        5005

Sample table: orders

ord_no      purch_amt   ord_date    customer_id  salesman_id
----------  ----------  ----------  -----------  -----------
70001       150.5       2012-10-05  3005         5002
70009       270.65      2012-09-10  3001         5005
70002       65.26       2012-10-05  3002         5001
70004       110.5       2012-08-17  3009         5003
70007       948.5       2012-09-10  3005         5002
70005       2400.6      2012-07-27  3007         5001
70008       5760        2012-09-10  3002         5001
70010       1983.43     2012-10-10  3004         5006
70003       2480.4      2012-10-10  3009         5003
70012       250.45      2012-06-27  3008         5002
70011       75.29       2012-08-17  3003         5007
70013       3045.6      2012-04-25  3002         5001

Sample Solution:

-- This query selects specific columns ('ord_no', 'cust_name', 'commission' with alias "Commission%", 
-- and 'purch_amt * commission' with alias "Commission") from the 'salesman', 'orders', and 'customer' tables.
-- It retrieves data where the 'customer_id' column in the 'orders' table matches the 'customer_id' column in the 'customer' table,
-- the 'salesman_id' column in the 'orders' table matches the 'salesman_id' column in the 'salesman' table,
-- and the 'grade' column in the 'customer' table is greater than or equal to 200.
SELECT ord_no, cust_name, commission AS "Commission%", purch_amt * commission AS "Commission"
-- Specifies the tables from which to retrieve the data (in this case, 'salesman', 'orders', and 'customer').
FROM salesman, orders, customer
-- Specifies the conditions for joining the tables and filtering the data.
WHERE orders.customer_id = customer.customer_id
  AND orders.salesman_id = salesman.salesman_id
  AND customer.grade >= 200;

Output of the query:

ord_no	cust_name	Commission%	Commission
70005	Brad Davis	0.15		360.0900
70010	Fabian Johnson	0.14		277.6802
70011	Jozy Altidor	0.13		9.7877
70001	Graham Zusi	0.13		19.5650
70007	Graham Zusi	0.13		123.3050
70012	Julian Green	0.13		32.5585

Code Explanation:

The said query in SQL that retrieves the order number, customer name, commission rate as "Commission%", and the calculated commission amount for salesmen who have customers with a grade of 200 or higher.
By joining the salesman, order, and customer tables on their respective ID fields, the query returns the columns that are specified in the SELECT statement for the salesman, order, and customer tables.
The WHERE clause filters the result set to only include orders made by customers with a grade of 200 or higher.

Explanation:

Visual presentation:

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Query Visualization:

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Previous SQL Exercise: Customers served by a salesman and commission.
Next SQL Exercise: Find all customers with orders on October 5, 2012.