Sql server 子查询返回了多个值。如何修复它？

我有这个查询来显示我想要的数据。但它给了我错误[Err]21000-[SQL Server]子查询返回的值超过1。当子查询在=、！=、=或者当子查询用作表达式时

数据：MCRX-MX023-LF-KGX，但当我输入其他数据时，没有错误

这是Sql server 2008

SELECT
    *
FROM
    (
        SELECT
            SupplierID,
            CurrencyAP AS Currency,
            (
                SELECT
                    UnitPrice
                FROM
                    Ms_PartPriceSupplier
                WHERE
                    SupplierID = x.SupplierID
                AND PartID = x.PartID
                AND LastUpdateDate = x.Tgl
            ) AS Price,
            PartID,
            (
                SELECT
                    PartnerName
                FROM
                    Ms_Partner
                WHERE
                    PartnerID = x.SupplierID
            ) SupplierName
        FROM
            (
                SELECT
                    PartID,
                    SupplierID,
                    CurrencyAP,
                    MAX (LastUpdateDate) AS Tgl
                FROM
                    Ms_PartPriceSupplier
                WHERE
                    PartID = 'MCRX-MX023-LF-KGX'
                GROUP BY
                    PartID,
                    SupplierID,
                    CurrencyAP
            ) x
    ) y
UNION ALL
    SELECT
        PartnerID AS SupplierID,
        '' AS Currency,
        0 AS Price,
        '' AS PartID,
        PartnerName AS SupplierName
    FROM
        Ms_Partner
    WHERE
        PartnerID NOT IN (
            SELECT DISTINCT
                SupplierID
            FROM
                Ms_PartPriceSupplier
            WHERE
                PartID = 'MCRX-MX023-LF-KGX'
        )

---

查询中

价格

和/或

供应商名称

列的选择子查询将返回多个值。它们应该只返回一个值（每行）

---

您可以在这些子查询中提供TOP（1），也可以调整它们的WHERE/HAVING子句中的条件。

您的一些子查询返回的值超过1

            SELECT
                UnitPrice
            FROM
                Ms_PartPriceSupplier
            WHERE
                SupplierID = x.SupplierID
            AND PartID = x.PartID
            AND LastUpdateDate = x.Tgl

            SELECT
                PartnerName
            FROM
                Ms_Partner
            WHERE
                PartnerID = x.SupplierID

根据您的需求在设备中添加

TOP（1）

或一些聚合功能，如

MIN

，

MAX

，例如：

        SELECT TOP (1)
            UnitPrice
        FROM
            Ms_PartPriceSupplier
        WHERE
            SupplierID = x.SupplierID
        AND PartID = x.PartID
        AND LastUpdateDate = x.Tgl

        SELECT TOP (1)
            PartnerName
        FROM
            Ms_Partner
        WHERE
            PartnerID = x.SupplierID

---

错误信息非常清楚。当您使用子查询而不是表而是值时，必须确保只返回一个值，否则将收到此错误消息

对您的查询的进一步调查显示您。。。你做错了。比如说,

    (
        SELECT
            PartnerName
        FROM
            Ms_Partner
        WHERE
            PartnerID = x.SupplierID
    ) SupplierName

在这里，您似乎希望获得与每个供应商ID关联的名称。在

SELECT

部分，您不应该以这种方式进行子查询。请记住：中的

首先得到评估，然后
其中
，然后
选择
。实际上，您在这里指示数据库尝试返回一个值作为SupplierName：这仅在您的查询只有一个SupplierID时才有效

你需要从连接开始思考。以下是您应该如何编写查询：

SELECT
    *
FROM
    (
        SELECT
            SupplierID,
            CurrencyAP AS Currency,
            Ms_PartPriceSupplier.UnitPrice AS Price,
            PartID,
            Ms_Partner.PartnerName as SupplierName
        FROM
            (
                SELECT
                    PartID,
                    SupplierID,
                    CurrencyAP,
                    MAX (LastUpdateDate) AS Tgl
                FROM
                    Ms_PartPriceSupplier
                WHERE
                    PartID = 'MCRX-MX023-LF-KGX'
                GROUP BY
                    PartID,
                    SupplierID,
                    CurrencyAP
            ) x
            inner join Ms_Partner on PartnerID = x.SupplierID
            inner join Ms_PartPriceSupplier on SupplierID = x.SupplierID AND PartID = x.PartID AND LastUpdateDate = x.Tgl
    ) y
UNION ALL
    SELECT
        PartnerID AS SupplierID,
        '' AS Currency,
        0 AS Price,
        '' AS PartID,
        PartnerName AS SupplierName
    FROM
        Ms_Partner
    WHERE
        PartnerID NOT IN (
            SELECT DISTINCT
                SupplierID
            FROM
                Ms_PartPriceSupplier
            WHERE
                PartID = 'MCRX-MX023-LF-KGX'
        )