Question

我有这个问题：

SELECT 
    s.id AS id, 
    s.item_id, 
    i.type_id AS type_id, 
    i.description AS description, 
    i.owner_id, 
    s.buyer_id, 
    i.receivedate, 
    i.statusdate, 
    i.baseprice, 
    i.salepercentage, 
    i.status_id, 
    s.posteddate, 
    s.closingdate, 
    s.discountdate, 
    s.discountrate, 
    t.description AS type_description, 
    st.description AS status_description
FROM 
    sale s
LEFT JOIN item i ON s.item_id=i.id 
LEFT JOIN TYPE t ON i.type_id=t.id 
LEFT JOIN STATUS st ON i.status_id=st.id 
WHERE s.flag_id != 2
GROUP BY s.id
ORDER BY s.closingdate;

它工作正常，但作为最后一步，我需要从另一个名为customer的表中提取连接的firstname和lastname字段，以便同时 i.owner_id和{ {1}}字段。

我已经接近使用以下内容：

s.buyer_id

当我使用customer表中的条目测试它时，如下所示：

SELECT 
    s.id AS id, 
    s.item_id, 
    i.type_id AS type_id, 
    i.description AS description, 
    i.owner_id, 
    s.buyer_id, 
    i.receivedate, 
    i.statusdate, 
    i.baseprice, 
    i.salepercentage, 
    i.status_id, 
    s.posteddate, 
    s.closingdate, 
    s.discountdate, 
    s.discountrate, 
    t.description AS type_description, 
    st.description AS status_description, 
    GROUP_CONCAT(CONCAT(c.firstname, ' ', c.lastname) ORDER BY i.owner_id, s.buyer_id)
FROM 
    sale s 
LEFT JOIN item i ON s.item_id=i.id 
LEFT JOIN TYPE t ON i.type_id=t.id 
LEFT JOIN STATUS st ON i.status_id=st.id 
LEFT JOIN CUSTOMER c ON i.owner_id=c.id OR s.buyer_id=c.id
WHERE s.flag_id != 2
GROUP BY s.id
ORDER BY s.closingdate;

销售表中的商品有：

id=3, firstname="John", lastname="Doe"
id=10, firstname="Jane", lastname="Do"

owner_id=3, buyer_id=10 owner_id=10, buyer_id=3列返回

GROUP_CONCAT()

我无法知道哪个是所有者，哪个是买家完全脱离逗号分隔的位置，因为我希望的结果是

Jane Do,John Doe
Jane Do,John Doe

用于销售商品。

是否可以确保返回的结果集将以受控顺序返回John Doe,Jane Do Jane Do,John Doe列表（即第一个客户将与GROUP_CONCAT()和第二个客户owner_id相关联1}}）？

Answer 1

我建议加入客户表两次。一次为买家，一次为所有者：

SELECT ...
   GROUP_CONCAT(CONCAT(buyer.firstname, ' ', buyer.lastname) AS buyers,
   GROUP_CONCAT(CONCAT(owner.firstname, ' ', owner.lastname) AS owners
...
LEFT JOIN customer AS buyer ON s.buyer_id=buyer.id
LEFT JOIN customer AS owner ON i.owner_id=owner.id

如果您需要将数据分开，请将其分开。

Answer 2

问题是你是混合所有者和买主只需单独加入;
只要为每个实例使用不同的别名，加入同一个表就没问题了。

SELECT 
  s.id AS id, s.item_id
  , i.type_id AS type_id, i.description AS description, i.owner_id
  , s.buyer_id
  , i.receivedate, i.statusdate, i.baseprice, i.salepercentage, i.status_id
  , s.posteddate, s.closingdate, s.discountdate, s.discountrate
  , t.description AS type_description
  , st.description AS status_description
  , GROUP_CONCAT(
      CONCAT(co.firstname, ' ', co.lastname,',',cb.firstname,' ',cb.lastname) 
      ORDER BY co.id,cb.id) as first_owner_than_buyer
FROM sale s 
LEFT JOIN item i ON s.item_id=i.id 
LEFT JOIN TYPE t ON i.type_id=t.id 
LEFT JOIN STATUS st ON i.status_id=st.id 
LEFT JOIN CUSTOMER co ON (i.owner_id=co.id)
LEFT JOIN CUSTOMER cb ON (s.buyer_id=cb.id)
WHERE s.flag_id != 2
GROUP BY s.id
ORDER BY s.closingdate;

MySQL在单个列中返回多个行值

2 个答案: