MySQL join two table with the maximum value on another field

问题

I have two table account and balance

/---------------------\
| cid | name | mobile |
|---------------------|
|  1  | ABC  | 12345  |
|---------------------|
|  2  | XYZ  | 98475  |
\---------------------/

/----------------------------\
| date       | cid | balance |
|----------------------------|
| 2013-09-19 |  1  |   5000  |
|----------------------------|
| 2013-09-19 |  2  |   7000  |
|----------------------------|
| 2013-09-20 |  1  |    300  |
|----------------------------|
| 2013-09-20 |  2  |   4500  |
|----------------------------|
| 2013-09-21 |  2  |    600  |
\----------------------------/

I would like to join this two table and get the balance of the maximum date for a particular cid.

Output result as -

/--------------------------------------------\
| cid | name | mobile | date       | balance |
|--------------------------------------------|
|  1  | ABC  | 12345  | 2013-09-20 |   300   |
|--------------------------------------------|
|  2  | XYZ  | 98475  | 2013-09-21 |   600   |
\--------------------------------------------/

回答1:

You need to use two sub-queries like this:

SELECT a.cid, a.name, a.mobile, b.date, b.balance
FROM account a 
JOIN
(
    SELECT b1.* FROM balance b1
    JOIN
    (
      SELECT cid, MAX(Date) As maxDate
      FROM balance
      GROUP BY cid
    ) b2
    ON b1.cid = b2.cid
    AND b1.date = b2.maxDate
) b
ON a.cid = b.cid;

Output:

CID	NAME	MOBILE	DATE	BALANCE
1	ABC	12345	September, 20 2013 00:00:00+0000	300
2	XYZ	98475	September, 21 2013 00:00:00+0000	600

See this SQLFiddle

回答2:

SELECT a.cid, a.name, a.mobile, MAX(b.date), b.balance 
FROM account AS a
INNER JOIN balance AS b
WHERE a.cid=b.cid 
GROUP BY cid;

Sorry I din't notice the balance column in 3rd table.

SELECT a.cid, a.name, a.mobile, b.date, b.balance 
FROM account AS a
INNER JOIN (
      SELECT c.date, c.cid, c.balance FROM balance AS c
      INNER JOIN (
            SELECT cid AS cid2, MAX(date) AS date2
            FROM balance
            GROUP BY cid2) AS d
ON c.cid=d.cid2 
AND c.date=d.date2
) AS b
ON a.cid=b.cid 
GROUP BY cid;--

回答3:

This following statement should get you the required result :

SELECT cid, name, mobile, MAX(date), blance  
FROM account
LEFT JOIN balance
ON account.cid = balance.cid
GROUP BY balance.cid

来源：https://stackoverflow.com/questions/18928992/mysql-join-two-table-with-the-maximum-value-on-another-field

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