Question

我不负责这个设计，但是我必须从这个类似于此的模式中提取数据（SQL Server 2000）：

CREATE TABLE contract
(
    contract_id int,
    account_id int,             /* account table */
    responsible_id int,         /* account table */
    holding_id int,             /* account table */
    billingaddress_id int,      /* address table */
    deliveryaddress_id int,     /* address table */
)

CREATE TABLE address
(
    address_id int,
    postalcode char(4),
)

CREATE TABLE account
(
    account_id int,
    firstname varchar(40),
    billingaddress_id int,      /* address table */
    deliveryaddress_id int,     /* address table */
)

合约表上的account_id，responsible_id和holding_id可以为null，共享值或具有不同的值。它可能有也可能没有结算和/或送货地址。帐户实体始终具有开票或送达地址，两者都可以相同。

我必须找到与合同相关的所有帐户（即合同具有相同的帐户，负责或持有ID作为帐户ID），并且与具有特定邮政编码的地址相关联（直接或通过合同）。

问题似乎是2倍：
a）检索与合同相关的帐户 b）过滤（a）的结果以获得与某个邮政编码相关的帐户

这不起作用，因为如果account_id与相关的邮政编码没有关联但是holding_id是，那么它将不会被返回：

FROM account
INNER JOIN contract
    ON account.account_id = 
        CASE WHEN NOT IsNull(contract.account_id) THEN contract.account_id 
        WHEN NOT IsNull(contract.responsible_id) THEN contract.responsible_id 
        ELSE contract.holding_id END

由于某些原因，这太慢了（FK没有编入索引 - 等待30分钟而且没有返回）：

FROM account
INNER JOIN contract
    ON account.account_id = contract.account_id
    OR account.account_id = contract.responsible_id
    OR account.account_id = contract.holding_id

唯一似乎有效的是UNION，但是我仍然遇到了按地址类型过滤结果的问题。

返回所需结果的最短方法是什么？目前，我倾向于创建一个临时表来存储中间数据。

Answer 1

SELECT  *
FROM    contract
WHERE   EXISTS
        (
        SELECT  NULL
        FROM    account
        JOIN    address
        ON      address_id IN (billingaddress_id, deliveryaddress_id)
        WHERE   account_id IN (account_id, responsible_id, holding_id)
                AND postalcode = @mycode
        )

要选择帐户，请使用：

SELECT  *
FROM    account ao
WHERE   EXISTS
        (
        SELECT  NULL
        FROM    (
                SELECT  account_id, responsible_id, holding_id
                FROM    contract c
                WHERE   c.account_id = ao.account_id
                UNION ALL
                SELECT  account_id, responsible_id, holding_id
                FROM    contract c
                WHERE   c.responsible_id = ao.account_id
                UNION ALL
                SELECT  account_id, responsible_id, holding_id
                FROM    contract c
                WHERE   c.holding_id = ao.account_id
                ) co
        JOIN    account ai
        ON      ai.account_id IN (co.account_id, co.responsible_id, co.holding_id)
        JOIN    address
        ON      address_id IN (billingaddress_id, deliveryaddress_id)
        WHERE   postalcode = @mycode
        )

<强>更新

由于您的列未编入索引，因此EXISTS在这种情况下效率不高，因为它不能作为IN重写。

您应该将所有连接条件重写为equijoins，以便HASH JOIN方法可用。

试试这个：

SELECT  a.account_id
FROM    (
        SELECT  account_id
        FROM    contract
        UNION
        SELECT  responsible_id
        FROM    contract
        UNION
        SELECT  holding_id
        FROM    contract
        ) c
JOIN    (
        SELECT  account_id, billingaddress_id AS address_id
        FROM    account
        UNION
        SELECT  account_id, deliveryaddress_id
        FROM    account
        ) a
ON      a.account_id = c.account_id
JOIN    address ad
ON      ad.address_id = a.address_id
WHERE   ad.postalcode = @mycode

Answer 2

最后，我选择了这样的事情：

FROM (
SELECT Account.*
FROM   (SELECT Contract.Account_Id          AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Account_Id          AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Account_Id          AS ForeignKey_Id,
               Contract.BillingAddress_Id AS Address_Id
        FROM   Contract) ContractInfo
       JOIN Account Account
         ON Account.Name_Id = ForeignKey_Id
       JOIN Address
         ON Address.Address_Id = ContractInfo.Address_Id
            AND Address.PostalCode = 'ABCDE'
UNION
SELECT Account.*
FROM   (SELECT Contract.Responsible_Id        AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Responsible_Id        AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Responsible_Id        AS ForeignKey_Id,
               Contract.BillingAddress_Id AS Address_Id
        FROM   Contract) ContractInfo
       JOIN Account Account
         ON Account.Name_Id = ForeignKey_Id
       JOIN Address
         ON Address.Address_Id = ContractInfo.Address_Id
            AND Address.PostalCode = 'ABCDE'
UNION
SELECT Account.*
FROM   (SELECT Contract.Holding_Id     AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Holding_Id     AS ForeignKey_Id,
               Contract.DeliveryAddress_Id AS Address_Id
        FROM   Contract
        UNION
        SELECT Contract.Holding_Id    AS ForeignKey_Id,
               Contract.BillingAddress_Id AS Address_Id
        FROM   Contract) ContractInfo
       JOIN Account Account
         ON Account.Name_Id = ForeignKey_Id
       JOIN Address
         ON Address.Address_Id = ContractInfo.Address_Id
            AND Address.PostalCode = 'ABCDE'
) Account

它比使用每行子选择或IN子句表现更好。

从表中检索数据，其中一个表有多个列指向另一个中的同一个主键？

2 个答案: