如何组合连接表结果中的列？

Question

我有一个如下所示的 mysql 表：

表支付类​​型

ID   PaymentCode   PaymentName
1      P1        CASH
2      P2        TRANSFER
3      P3        CREDIT CARD

餐桌人

ID   ID_PERSON   PersonName
1      123        GEORGE
2      124        HENRY
3      125        MICHAEL
4      126        ANNA

表 INVOICE_IN

ID   ID_INVOICE_IN   Person_ID  Amount PaymentType_ID
1      II-001            1       100      1
2      II-002            2       200      1
3      II-003            4       300      2

表 INVOICE_OUT

ID   ID_INVOICE_OUT   Person_ID  Amount     PaymentType_ID
1      IO-001                 1       500      2
1      IO-002                 3       600      3

我想要这样的结果：

ID_INVOICE_IN PaymentCode  PersonName  Amount ID_INVOICE_OUT PaymentCode  PersonName  Amount
II-001            P1         George     100        IO-001     P2          George      500 
II-002            P1         Henry      200        IO-002     P3       Michael       600 
II-003            P2         Anna       300         NULL      NULL       NULL      NULL

我有一个这样的查询：

SELECT INVOICE_IN.ID_INVOICE_IN, PaymentType.PaymentCode, PERSONS.PersonName, INVOICE_IN.Amount FROM INVOICE_IN LEFT JOIN PaymentType ON PaymentType.id = INVOICE_IN.PaymentType_ID LEFT JOIN PERSONS ON PERSONS.id = INVOICE_IN.Person_ID

查询成功显示 invoice_in 的 4 列。

我也有这样的查询：

SELECT INVOICE_OUT.ID_INVOICE_OUT, PaymentType.PaymentCode, PERSONS.PersonName, INVOICE_OUT.Amount FROM INVOICE_OUT LEFT JOIN PaymentType ON PaymentType.id = INVOICE_OUT.PaymentType_ID LEFT JOIN PERSONS ON PERSONS.id = INVOICE_OUT.Person_ID

查询成功显示 4 列 invoice_out

我需要在result1（invoice_in）和result2（invoice_out）之间合并，所以查询的结果有8列。

Answer 1

如果我的理解正确，您似乎想要做的是显示彼此相邻的不相关数据集。

一种方法是对每个集合中的行进行编号，然后将较大的集合作为左侧进行左连接。 （更好的方法是使用full outer join，但 MySQL 不支持，尽管使用带联合的左/右连接可以实现相同的效果）。在 MySQL 中，您可以使用用户变量对行进行编号。

此查询给出了您的示例的结果，尽管我并没有真正看到并排显示不相关数据的意义。 （如果它真的不相关......问题中没有任何内容表明它是相关的）。

select 
  t1.id_invoice_in, t1.paymentcode, t1.personname, t1.amount,
  t2.id_invoice_out, t2.paymentcode, t2.personname, t2.amount  
from (
  select     
    id_invoice_in, paymentcode, personname, amount,
    (@r1 := @r1 + 1) as r1
  from invoice_in 
  join paymenttype pt on pt.id = paymenttype_id 
  join persons p on p.id = person_id
  ,(select @r1 := 0) r
) t1 left join (
  select 
    id_invoice_out, paymentcode, personname, amount,
    (@r2 := @r2 + 1) as r2
  from invoice_out 
  join paymenttype pt on pt.id = paymenttype_id 
  join persons p on p.id = person_id
  ,(select @r2 := 0) r
) t2 on t1.r1 = t2.r2;

Sample SQL Fiddle

Answer 2

SELECT 
    `In`.`ID_INVOICE_IN`, 
    `PayI`.`PaymentCode`, 
    `PersI`.`PersonName`, 
    `In`.`Amount`, 
    `Out`.`ID_INVOICE_OUT`, 
    `PayO`.`PaymentCode`, 
    `PersI`.`PersonName`, 
    `Out`.`Amount` 
FROM
    `INVOICE_IN`  AS `In`,
    `INVOICE_OUT` AS `Out`,
    `PERSONS`     AS `PersI`,
    `PERSONS`     AS `PersO`,
    `PaymentType` AS `PayI`,
    `PaymentType` AS `PayO`
WHERE
    `In`.`ID`              = `Out`.`ID`   AND
    `In`.`Person_ID`       = `PersI`.`ID` AND
    `Out`.`Person_ID`      = `PersO`.`ID` AND
    `In`.`PaymentCode_ID`  = `PayI`.`ID`  AND
    `Out`.`PaymentCode_ID` = `PayO`.`ID`
ORDER BY
    `In`.`ID_INVOICE_IN`