Question

我有四个链接的表。每个购物车项目的itemStatus表可以有多个记录，以显示其历史记录（例如，购买，处理，运输，交付）。商店表中输入购物车项目名称。订单表定义了订单中的所有购物车项目。

要显示订单中每个购物车项目的最新状态（不是整个历史记录），我只需要获取itemStatus的最后一条记录。我正在使用子查询来获取itemStatus表的记录，但无法弄清楚如何获取最后一条记录。玩下面的代码，我最终总是得到第一条记录：

SELECT
    tblOrders.id,tblOrders.status as orderStatus,tblOrders.created,tblCart.id AS cartID,tblCart.status AS cartStatus,tblCart.qty,tblCart.price,tblShop.title,tblItem.itemStatus 
FROM
    ".PREFIX."Orders tblOrders 
LEFT JOIN
    ".PREFIX."Cart tblCart ON tblOrders.id=tblCart.OID 
LEFT JOIN
    ".PREFIX."Shop tblShop ON tblCart.PID=tblShop.id 
LEFT JOIN
    (SELECT
        CID,status as itemStatus
    FROM
        ".PREFIX."ItemStatus
    WHERE
        status IN ('pending','refunded','cancelled','purchased','backordered','shipping','delivered')
GROUP BY CID
    ORDER BY
        created DESC
    ) tblItem ON tblCart.id=tblItem.CID 
WHERE
    tblOrders.status<>'disabled' AND tblCart.status='purchased' AND tblCart.BID='".$gbl_user['id']."' 
ORDER BY
    tblOrders.updated DESC

如上所示，我尝试使用'GROUP BY'子句来限制子查询返回的记录数，但是不会产生期望的结果。我也尝试过在子查询中放置'LIMIT 1'子句，但这仅将返回的记录数限制为1（因此任何其他购物车商品都不会以状态结尾）。任何帮助将不胜感激！

更新：

对于重复标记，我尝试使用MAX（）语句更新代码，并删除“ ORDER BY”，如下所示：

SELECT
    tblOrders.id,tblOrders.status as orderStatus,tblOrders.created,tblCart.id AS cartID,tblCart.status AS cartStatus,tblCart.qty,tblCart.price,tblShop.title,tblItem.itemStatus 
FROM
    ".PREFIX."Orders tblOrders 
LEFT JOIN
    ".PREFIX."Cart tblCart ON tblOrders.id=tblCart.OID 
LEFT JOIN
    ".PREFIX."Shop tblShop ON tblCart.PID=tblShop.id 
LEFT JOIN
    (SELECT
        CID,status as itemStatus,MAX(created) as itemCreated
    FROM
        ".PREFIX."ItemStatus
    WHERE
        status IN ('pending','refunded','cancelled','purchased','backordered','shipping','delivered')
GROUP BY CID
    ) tblItem ON tblCart.id=tblItem.CID 
WHERE
    tblOrders.status<>'disabled' AND tblCart.status='purchased' AND tblCart.BID='".$gbl_user['id']."' 
ORDER BY
    tblOrders.updated DESC

更新2：

我提供了可以解决该问题的实际代码，但由于某些原因未获批准。我在下面发布了正确的代码：

SELECT
    tblOrders.id, tblOrders.status as orderStatus, tblOrders.created,
    tblCart.id AS cartID, tblCart.status AS cartStatus,tblCart.qty,
    tblCart.price, tblShop.title, tblItem.status as itemStatus 
FROM
    ".PREFIX."Orders tblOrders 
LEFT JOIN
    ".PREFIX."Cart tblCart ON tblOrders.id=tblCart.OID 
LEFT JOIN
    ".PREFIX."Shop tblShop ON tblCart.PID=tblShop.id 
LEFT JOIN
    ".PREFIX."ItemStatus tblItem ON tblCart.id=tblItem.CID 
JOIN (
    SELECT
        CID, MAX(created) AS maxCreated
    FROM
        ".PREFIX."ItemStatus
    WHERE
        status IN ('pending','refunded','cancelled','purchased','backordered','shipping','delivered')
    GROUP BY
        CID
) tblMaxItem ON tblItem.CID=tblMaxItem.CID AND tblItem.created=tblMaxItem.maxCreated
WHERE
    tblOrders.status<>'disabled' AND tblCart.status='purchased' AND tblCart.BID='".$gbl_user['id']."' 
ORDER BY
    tblOrders.updated DESC

Answer 1

您需要同时与ItemStatus和一个子查询结合使用，该子查询获取每个项目的最新日期，以便您可以从该行中获取其他列的列。

SELECT
    tblOrders.id, tblOrders.status as orderStatus, tblOrders.created,
    tblCart.id AS cartID, tblCart.status AS cartStatus,tblCart.qty,
    tblCart.price, tblShop.title, tblItem.status AS itemStatus
FROM
    ".PREFIX."Orders tblOrders 
LEFT JOIN
    ".PREFIX."Cart tblCart ON tblOrders.id=tblCart.OID 
LEFT JOIN
    ".PREFIX."Shop tblShop ON tblCart.PID=tblShop.id 
LEFT JOIN
    ".PREFIX."ItemStatus tblItem ON tblCart.id=tblItem.CID 
LEFT JOIN (
    SELECT
        CID, MAX(created) AS maxCreated
    FROM
        ".PREFIX."ItemStatus
    WHERE
        status IN ('pending','refunded','cancelled','purchased','backordered','shipping','delivered')
    GROUP BY
        CID
) tblMaxItem ON tblItem.CID=tblMaxItem.CID AND tblItem.created=tblMaxItem.maxCreated
WHERE
    tblOrders.status<>'disabled' AND tblCart.status='purchased' AND tblCart.BID='".$gbl_user['id']."' 
ORDER BY
    tblOrders.updated DESC

将子查询结果集限制为最后一条记录

1 个答案: