SQL Subquery Exercises: Find all the salesmen worked for only one customer

SQL SUBQUERY: Exercise-17 with Solution

17. From the following tables write a SQL query to find salespeople who deal with a single customer. Return salesman_id, name, city and commission.

Sample table: Customer

Sample table: Salesman

Sample Solution:

SELECT * 
FROM salesman 
WHERE salesman_id IN (
   SELECT DISTINCT salesman_id 
   FROM customer a 
   WHERE NOT EXISTS (
      SELECT * FROM customer b 
      WHERE a.salesman_id=b.salesman_id 
      AND a.cust_name<>b.cust_name));

Output of the Query:

salesman_id	name		city	commission
5005		Pit Alex	London	0.11
5006		Mc Lyon		Paris	0.14
5007		Paul Adam	Rome	0.13
5003		Lauson Hen	San Jose0.12

Explanation:

Practice Online

Query Visualization:

Duration:

Rows:

Cost:

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