SQL Exercise: Salesmen works either for one or more customer or not
SQL JOINS: Exercise-12 with Solution
Write a SQL statement to generate a list in ascending order of salespersons who work either for one or more customers or have not yet joined any of the customers.
Sample table: customer
Sample table: salesman
Sample Solution:
SELECT a.cust_name,a.city,a.grade,
b.name AS "Salesman", b.city
FROM customer a
RIGHT OUTER JOIN salesman b
ON b.salesman_id=a.salesman_id
ORDER BY b.salesman_id;
Output of the Query:
cust_name city grade Salesman city Brad Davis New York 200 James Hoog New York Nick Rimando New York 100 James Hoog New York Graham Zusi California 200 Nail Knite Paris Julian Green London 300 Nail Knite Paris Geoff Cameron Berlin 100 Lauson Hen San Jose Brad Guzan London Pit Alex London Fabian Johnson Paris 300 Mc Lyon Paris Jozy Altidor Moscow 200 Paul Adam Rome
Explanation:
The said SQL query is performing a right outer join on the customer table alias a and the salesman table alias b on the 'salesman_id' column. It is then selecting the 'cust_name', 'city', and 'grade' columns from the customer table, and the 'name' and 'city' columns from the salesman table. The result is ordered by the 'salesman_id' column.
This query will select all the rows from the salesman table and any matching rows from the customer table and returning the results in the order of salesman_id. If there is no match, it will return NULL for the non-matching columns of customer table.
Visual Explanation:
Practice Online
Query Visualization:
Duration:
Rows:
Cost:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous SQL Exercise: Find customers who have placed no order or one or more.
Next SQL Exercise: Salesmen who works either for one or more customer.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
SQL: Tips of the Day
Grouped LIMIT in PostgreSQL: Show the first N rows for each group?
db=# SELECT * FROM xxx; id | section_id | name ----+------------+------ 1 | 1 | A 2 | 1 | B 3 | 1 | C 4 | 1 | D 5 | 2 | E 6 | 2 | F 7 | 3 | G 8 | 2 | H (8 rows)
I need the first 2 rows (ordered by name) for each section_id, i.e. a result similar to:
id | section_id | name ----+------------+------ 1 | 1 | A 2 | 1 | B 5 | 2 | E 6 | 2 | F 7 | 3 | G (5 rows)
PostgreSQL v9.3 you can do a lateral join
select distinct t_outer.section_id, t_top.id, t_top.name from t t_outer
join lateral (
select * from t t_inner
where t_inner.section_id = t_outer.section_id
order by t_inner.name
limit 2
) t_top on true
order by t_outer.section_id;
Database: PostgreSQL
Ref: https://bit.ly/3AfYwZI
- Weekly Trends
- Python Interview Questions and Answers: Comprehensive Guide
- Scala Exercises, Practice, Solution
- Kotlin Exercises practice with solution
- MongoDB Exercises, Practice, Solution
- SQL Exercises, Practice, Solution - JOINS
- Java Basic Programming Exercises
- SQL Subqueries
- Adventureworks Database Exercises
- C# Sharp Basic Exercises
- SQL COUNT() with distinct
- JavaScript String Exercises
- JavaScript HTML Form Validation
- Java Collection Exercises
- SQL COUNT() function
- SQL Inner Join
We are closing our Disqus commenting system for some maintenanace issues. You may write to us at reach[at]yahoo[dot]com or visit us at Facebook