Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

MySQL - Join last row of related table

Tags:

sql

mysql

I have a problem that I have searched for and can't find answers that offer any help.

There are 3 tables: orders, customers, and teams. Each order has a customer and a team. My problem is that for each customer, I am trying to get their total orders, and then the team that was assigned to their last order.

My query so far (works fine):

SELECT c.id, MAX(o.timestamp) AS "Last Order", COUNT(o.id) AS "Total Orders", SUM(o.price) AS "Total Spend"
FROM orders o
LEFT JOIN customers c ON o.customer = c.id
WHERE o.timestamp > '2012-01-01 00:00:00'
GROUP BY c.id
ORDER BY c.id

I can't figure out how to join the team.name for the last order they placed, without affecting the rest of the query that I have.

Sample Tables and Desired Result:

Customers:

╔════╦═════════════╗
║ ID ║    NAME     ║
╠════╬═════════════╣
║  1 ║ John Smith  ║
║  2 ║ Jim Jimmers ║
╚════╩═════════════╝

Teams:

╔════╦═════════════╗
║ ID ║    NAME     ║
╠════╬═════════════╣
║  1 ║ Red         ║
║  2 ║ Blue        ║
╚════╩═════════════╝

Orders:

╔═══════╦═════════════════════╦══════════╦══════╦═══════╗
║  ID   ║       TIMESTAMP     ║ CUSTOMER ║ TEAM ║ VALUE ║
╠═══════╬═════════════════════╬══════════╬══════╬═══════╣
║ 34656 ║ 2012-03-04 14:23:44 ║        1 ║    2 ║    20 ║
║ 37345 ║ 2012-04-12 11:32:07 ║        2 ║    2 ║    25 ║
║ 38220 ║ 2012-07-18 09:53:54 ║        1 ║    2 ║    15 ║
║ 39496 ║ 2012-07-03 10:11:32 ║        1 ║    1 ║    38 ║
║ 41752 ║ 2012-09-17 19:34:05 ║        1 ║    2 ║     9 ║
║ 43734 ║ 2012-11-23 07:52:12 ║        2 ║    1 ║    20 ║
╚═══════╩═════════════════════╩══════════╩══════╩═══════╝

How do I select a result like:

╔════╦═════════════╦═════════════════════╦═══════════╦══════════════╦═════════════╗
║ ID ║    NAME     ║      LAST_ORDER     ║ TEAM_NAME ║ TOTAL_ORDERS ║ TOTAL_SPEND ║
╠════╬═════════════╬═════════════════════╬═══════════╬══════════════╬═════════════╣
║  1 ║ John Smith  ║ 2012-09-17 19:34:05 ║ Blue      ║           4  ║          82 ║
║  2 ║ Jim Jimmers ║ 2012-11-23 07:52:12 ║ Red       ║           2  ║          45 ║
╚════╩═════════════╩═════════════════════╩═══════════╩══════════════╩═════════════╝
like image 618
BadHorsie Avatar asked Dec 30 '25 18:12

BadHorsie


1 Answers

You can use a query similar to this:

select c.id,
  c.name,
  o1.Last_Order,
  t.name Team_Name,
  o3.Total_Orders,
  o3.Total_Spend
from customers c
inner join
(
  select max(timestamp) Last_Order,
    max(id) Last_id,
    customer
  from orders
  WHERE timestamp > '2012-01-01 00:00:00'
  group by customer
) o1
  on c.id = o1.customer
inner join orders o2
  on c.id = o2.customer
  and o1.Last_Order = o2.timestamp
  and o1.Last_id = o2.id
inner join teams t
  on o2.team = t.id
inner join
(
  select count(team) Total_Orders,
    sum(value) Total_Spend,
    customer
  from orders 
  WHERE timestamp > '2012-01-01 00:00:00'
  group by customer
) o3
  on c.id = o3.customer
WHERE o2.timestamp > '2012-01-01 00:00:00'

See SQL Fiddle with Demo

like image 67
Taryn Avatar answered Jan 01 '26 11:01

Taryn



Donate For Us

If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!