SQL Exercises: Show all the orders for the London-based salesman

SQL SUBQUERY: Exercise-2 with Solution

2. From the following tables write a SQL query to find all orders generated by London-based salespeople. Return ord_no, purch_amt, ord_date, customer_id, salesman_id.

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
5003         Lauson Hen  San Jose    0.12
5007         Paul Adam   Rome        0.13

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:

-- Selecting all columns from the 'orders' table
SELECT *
-- Specifying the table to retrieve data from ('orders')
FROM orders
-- Filtering the results based on the condition that 'salesman_id' is in the result of a subquery
WHERE salesman_id IN
    -- Subquery: Selecting 'salesman_id' from the 'salesman' table where 'city' is 'London'
    (SELECT salesman_id 
     FROM salesman 
     WHERE city='London');

Output of the Query:

ord_no	purch_amt	ord_date	customer_id	salesman_id
70009	270.65		2012-09-10	3001		5005

Explanation:

The said SQL statement is selecting all columns (*) from the orders table where the 'salesman_id' is one of the 'salesman_id' s in the salesman table where the city is 'London'.
It first looks in the salesman table to find all the 'salesman_id' s of the salesman which are located in 'London', then uses the IN operator to filter the rows in the orders table where the 'salesman_id' column is in the list of 'salesman_id' s obtained from the first subquery.

Visual Explanation:

Practice Online

Sample Database: inventory

Query Visualization:

Duration:

Rows:

Cost:

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