连接SQL查询的单行结果

Question

我有一个SQL查询：

SELECT p.id, p.firstname, p.lastname, p.emailcollected, p.phone, e.accountid, e.accounttype
FROM player p
JOIN bankaccountinfo e ON p.id = e.playerid
WHERE ( ( p.createtime > 0 AND p.createtime < 2000000000 ) OR
        ( p.updatetime > 0 AND p.updatetime < 200000000000000 ) )
  AND e.accounttype IN ( 5002,5003 ) ;

这将返回2行，结果是帐户类型有2种枚举类型：

+--------------+-----------+----------+----------------+------------+---------------+-------------+
| id           | firstname | lastname | emailcollected | phone      | accountnumber | accounttype |
+--------------+-----------+----------+----------------+------------+---------------+-------------+
|            9 | dineshND  | NineND   |     1536064455 | 5175761111 | 102323        |        5002 |
|            9 | dineshND  | NineND   |     1536064455 | 5175761111 | 102324        |        5003 |
+--------------+-----------+----------+----------------+------------+---------------+-------------+

但是我希望帐户号基于帐户类型在一行中显示为SavingAccountNumber和CheckingAccountNumber。

预期结果：

+--------------+-----------+----------+----------------+------------+---------------------+-----------------------+
| id           | firstname | lastname | emailcollected | phone      | savingaccountnumber | checkingaccountnumber |
+--------------+-----------+----------+----------------+------------+---------------------+-----------------------+
|            9 | dineshND  | NineND   |     1536064455 | 5175761111 | 102323              |            102324     |
+--------------+-----------+----------+----------------+------------+---------------------+-----------------------+

• 帐户类型为5003时的Savingaccountnumber列
• 当accountype为5002时，检查accountnumber列
• My Mysql版本： mysql Ver 14.12 Distrib 5.0.51a，用于使用readline 5.2的debian-linux-gnu（i486）

Answer 1

从样本数据和预期结果中，您可以尝试使用条件加重功能

SELECT id,
    firstname,
    lastname,
    emailcollected,
    phone,
    MAX(CASE WHEN accounttype = 5003 THEN accountid END) savingaccountnumber,
    MAX(CASE WHEN accounttype = 5002 THEN accountid END) checkingaccountnumber
FROM (
    SELECT p.id, p.firstname, p.lastname, p.emailcollected, p.phone, e.accountid, e.accounttype
    FROM player p
    JOIN bankaccountinfo e ON p.id = e.playerid
    WHERE ( ( p.createtime > 0 AND p.createtime < 2000000000 ) OR
            ( p.updatetime > 0 AND p.updatetime < 200000000000000 ) )
      AND e.accounttype IN ( 5002,5003 ) 
) t1 
GROUP BY  id,firstname,lastname,emailcollected,phone

Answer 2

您需要两次加入bankaccountinfo才能在一排中得到东西：一次用于支票，一次用于储蓄。 假设您（a）即使缺少帐户记录也要返回一行，并且（b）在bankaccountinfo为playerid, accounttype定义了一个唯一键：

SELECT
    p.id,
    p.firstname,
    p.lastname,
    p.emailcollected,
    p.phone,
    e1.accountid checkingaccountnumber,
    e2.accountid savingaccountnumber
FROM
    player p
LEFT JOIN
    bankaccountinfo e1
ON
    p.id = e1.playerid
    AND e1.accounttype = 5002
LEFT JOIN
    bankaccountinfo e2
ON
    p.id = e2.playerid
    AND e2.accounttype = 5003
WHERE
    (p.createtime > 0 AND p.createtime < 2000000000)
    OR (p.updatetime > 0 AND p.updatetime < 200000000000000)

无论哪种方式，都要仔细研究JOIN和IN的作用，以了解为什么会得到两个结果。