Summing multiple columns - unexpected results - mysql

Question

Why
Does this give incorrect results?
SELECT
people.name,
SUM(allorders.TOTAL),
SUM(allorders.DISCOUNT),
SUM(allorders.SERVICECHARGE),
SUM(payments.AMOUNT)
FROM
people
INNER JOIN
allorders ON allorders.CUSTOMER = people.ID
INNER JOIN
payments ON payments.CUSTOMER = people.ID
WHERE
people.ID = 7 AND allorders.VOIDED = 0 AND payments.VOIDED = 0
Gives: (the name), 1644000, 1100000, 50000, 1485000
If I do it two tables at a time (INNER JOIN people ON allorders.CUSTOMER = people.ID) in separate queries, I get the correct results. I don't don't even know where the numbers I get come from. Like:
SELECT
people.name,
SUM(allorders.TOTAL),
SUM(allorders.DISCOUNT),
SUM(allorders.SERVICECHARGE)
FROM
people
INNER JOIN
allorders ON allorders.CUSTOMER = people.ID
WHERE people.ID = 7 AND allorders.VOIDED = 0
Gives: (the name), 822000, 550000, 25000
SELECT
people.name,
SUM(payments.AMOUNT)
FROM
people
INNER JOIN payments ON payments.CUSTOMER = people.ID
WHERE people.ID = 7 AND payments.VOIDED = 0
Gives: (the name), 297000
It looks like it doubles, but I don't know why.
The odd thing is I have a similar query that does this sum correctly. I'll post it, but it's a bit complex. Here goes:
SELECT
t1.IDENTIFIER,
ifnull(t1.NAME,""),
t1.PRICE,
t1.GUESTS,
t1.STATUS,
ifnull(t1.NOTE,""),
t1.LINK,
ifnull(t1.EDITOR,""),
concat(t2.FIRSTNAME,"",t2.LASTNAME),
t2.ID,
t3.ID,
ifnull(t1.EMAIL,""),
ifnull(t3.PHONE,""),
ifnull(SUM(p1.AMOUNT),0),
ifnull(SUM(o1.DISCOUNT),0),
ifnull(SUM(o1.TOTAL),0),
ifnull(SUM(o1.SERVICECHARGE),0)
FROM
tables t1
INNER JOIN
people t2 ON t1.SELLER = t2.ID
INNER JOIN
people t3 ON t1.CUSTOMER = t3.ID
INNER JOIN
orderpaymentinfo ON orderpaymentinfo.TABLEID = t1.IDENTIFIER
INNER JOIN
payments p1 ON orderpaymentinfo.PAYMENTID = p1.PAYMENTID
INNER JOIN
allorders o1 ON o1.ORDERID = orderpaymentinfo.ORDERID
WHERE
p1.VOIDED = 0 AND o1.VOIDED = 0 AND t1.DATE = "2014-12-20"
GROUP BY t1.IDENTIFIER
The latter statement does the same join, only it uses an additional helper-table. I'm sorry it's a bit poorly formatted (I'm not great with SO's formatter), but if someone can tell me the difference between the logic in these two statements and how one can be completely wrong while the other right, I'd be very happy.
In response to answer:
Result 1:
Name - 5
Result 2:
Name - 2
Result 3:
Name - 10
Result 4 is truncated in phpMyAdmin - where would I get this easily?
Table structure for the three tables looks like:
SHOW create on the way.

Answer 1

Okay, so I am pretty sure you've a join condition that's basically exploding your result set into something like a Cartesian product. Here's what I think you should try
First, run the following and share the output:
SELECT p.name,COUNT(*)
FROM people as p
INNER JOIN allorders AS a
ON a.CUSTOMER = p.ID
WHERE p.ID = 7 AND a.VOIDED = 0
GROUP BY p.name
Then run
SELECT p.name,COUNT(*)
FROM people AS p
INNER JOIN payments AS pay
ON pay.CUSTOMER = p.ID
WHERE p.ID = 7 AND pay.VOIDED = 0
GROUP BY p.name
Then run
SELECT
p.name,
COUNT(*)
FROM
people as p
INNER JOIN
allorders as a ON a.CUSTOMER = p.ID
INNER JOIN
payments as pay ON pay.CUSTOMER = p.ID
WHERE
p.ID = 7 AND a.VOIDED = 0 AND pay.VOIDED = 0
GROUP BY p.name
Last run the following
SHOW CREATE TABLE people;
SHOW CREATE TABLE payments;
SHOW CREATE TABLE allorders;
The problem is that you don't have the correct understanding of your data. You need to give us a bit more info about the data and the relationships, and the output I've described here should help. Mine is not an answer. But if you run these queries and paste the output of them, you should be able to get an answer, either from me or someone else.
Based on the discussion and edits above, please try:
SELECT
p.name,
SUM(o.TOTAL),
SUM(o.DISCOUNT),
SUM(o.SERVICECHARGE),
MAX(pay.amt)
FROM
people as p
INNER JOIN
allorders AS o ON o.CUSTOMER = p.ID
INNER JOIN (SELECT customer,
SUM(amount) as amt
FROM payments
WHERE voided = 0 AND customer = 7
GROUP BY customer) AS pay
ON pay.customer = p.id
WHERE
p.ID = 7 AND o.VOIDED = 0
GROUP BY p.name
You could also do a subquery in your SELECT statement, but it's pretty obnoxious imo. You could also do min(pay.amt) or avg or even just leave the aggregate out altogether. The above should work... even though there are cleaner ways. I'm providing this answer so you can reason about why you were getting the unexpected result... actually optimizing your query is a different question that you can dive into later, once you've had a chance to look over this