I have three tables like this:
receipts
+------------+-------+------+------------+-----------+
| customerId | recID | plan | recDate | processed |
+------------+-------+------+------------+-----------+
| 9742 | 900 | 1 | 1178726955 | 0 |
| 2188 | 899 | 1 | 1178670358 | 0 |
| 2657 | 898 | 1 | 1178639090 | 0 |
| 9699 | 897 | 1 | 1178627303 | 0 |
| 1247 | 896 | 1 | 1178570875 | 0 |
+------------+-------+------+------------+-----------+
customer
+-------------------------------+----------+-----------+
| Email | LastName | FirstName |
+-------------------------------+----------+-----------+
| user1@domain.com | lname | fname |
| user2@domain.com | lname | fname |
| user3@domain.com | lname | fname |
| user4@domain.com | lname | fname |
| user5@domain.com | lname | fname |
+-------------------------------+----------+-----------+
user
+----------+--------------+-------------+
| Approved | UserUpgraded | UpgradeDate |
+----------+--------------+-------------+
| 1 | 1 | 1176134955 |
| 1 | 1 | 1176078358 |
| 1 | 1 | 1176047090 |
| 1 | 1 | 1176035303 |
| 1 | 1 | 1175978875 |
+----------+--------------+-------------+
each table is actually much bigger than that, over 10,000 entries ... now i need to get all three table's info at once ... since there is no index associated with any of those (poorly designed ... not by me) i am forced to use the WHERE clause.
now this is where i get messed up ... this query:
SELECT
DISTINCT receipts.customerId,
receipts.recID,
receipts.plan,
receipts.recDate,
receipts.processed,
customer.Email,
customer.LastName,
customer.FirstName
FROM
`receipts`,
`customer`
WHERE
receipts.customerId = customer.CustomerId
GROUP BY
receipts.customerId
ORDER BY
receipts.recID DESC
LIMIT
5;
produces the following result:
+------------+-------+------+------------+-----------+-------------------------------+----------+-----------+
| customerId | recID | plan | recDate | processed | Email | LastName | FirstName |
+------------+-------+------+------------+-----------+-------------------------------+----------+-----------+
| 9742 | 900 | 1 | 1178726955 | 0 | user1@domain.com | lname | fname |
| 2188 | 899 | 1 | 1178670358 | 0 | user2@domain.com | lname | fname |
| 2657 | 898 | 1 | 1178639090 | 0 | user3@domain.com | lname | fname |
| 9699 | 897 | 1 | 1178627303 | 0 | user4@domain.com | lname | fname |
| 1247 | 896 | 1 | 1178570875 | 0 | user5@domain.com | lname | fname |
+------------+-------+------+------------+-----------+-------------------------------+----------+-----------+
5 rows in set (0.01 sec)
which is fine ... but as soon as i add my third and last table into play .. the query takes about 2 mins to process and uses 50+% CPU ... this is the query i try to run:
SELECT
DISTINCT receipts.customerId,
receipts.recID,
receipts.plan,
receipts.recDate,
receipts.processed,
customer.Email,
customer.LastName,
customer.FirstName,
user.Approved,
user.UserUpgraded,
user.UpgradeDate
FROM
`receipts`,
`customer`,
`user`
WHERE
receipts.customerId=customer.CustomerId AND
customer.Email=user.UserEmail
GROUP BY
receipts.customerId
ORDER BY
receipts.recID DESC;
LIMIT
5;
am i doing something wrong ? any help would be appreciated
p.s. the reason im doing distinct and group by customer id from the receipts table is because there are multiple receipts for each customer ... and i want to get the latest one!
p.s.s. the user table also has an email column, thats how the user and customer tables are linked ...
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