SQL Exercise: Customer who works either through a salesman or by own
8. Customer & Salesman Sorted by Customer_ID
From the following tables write a SQL query to display the customer name, customer city, grade, salesman, salesman city. The results should be sorted by ascending customer_id.
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: 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 Solution:
-- Selecting specific columns from the 'customer' and 'salesman' tables
SELECT a.cust_name, a.city, a.grade,
b.name AS "Salesman", b.city
-- Specifying the tables to retrieve data from ('customer' as 'a' and 'salesman' as 'b')
FROM customer a
-- Performing a left join based on the salesman_id, including unmatched rows from 'customer'
LEFT JOIN salesman b
ON a.salesman_id = b.salesman_id
-- Sorting the result set by customer_id in ascending order
ORDER BY a.customer_id;
Output of the Query:
cust_name city grade Salesman city Brad Guzan London Pit Alex London Nick Rimando New York 100 James Hoog New York Jozy Altidor Moscow 200 Paul Adam Rome Fabian Johnson Paris 300 Mc Lyon Paris Graham Zusi California 200 Nail Knite Paris Brad Davis New York 200 James Hoog New York Julian Green London 300 Nail Knite Paris Geoff Cameron Berlin 100 Lauson Hen San Jose
Explanation:
The said SQL query that uses the LEFT JOIN clause to combine rows from two tables: customer and salesman.
The query retrieves the cust_name, city, grade, name, and city from the two tables where the salesman_id from the customer table matches the salesman_id from the salesman table.
The query also uses the AS keyword to rename the name column as 'Salesman'.
The result of the query will show all rows from the customer table and the matching rows from the salesman table, and any customer without a matching salesman will have NULL values for the salesman columns.
The query also uses the ORDER BY clause to sort the result by customer_id.
Visual Explanation:
Practice Online
Query Visualization:
Duration:
Rows:
Cost:
For more Practice: Solve these Related Problems:
- Write a SQL query to display customer name, customer city, grade, salesperson name, and salesperson city sorted in ascending order by customer_id.
- Write a SQL query to list customer and salesperson details sorted by customer_id, while converting customer names to uppercase.
- Write a SQL query to retrieve customer and salesperson information, ordering the result by customer_id and excluding records with a missing grade.
- Write a SQL query to fetch a report of customer and salesperson details, grouping the results by customer city and sorting by customer_id.
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Previous SQL Exercise: Join within the tables salesman, customer and orders.
Next SQL Exercise: Customers who holds a grade less than 300.
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