Question

我有两张桌子：表1

Customer|Seller Currency|Invoice #|Invoice Currency

ABC     |USD            |123      |MXP

我有第二张表，用于存储客户的银行帐户

表2

Customer | Bank Account | Currency
ABC      | BANK1        | MXP
ABC      | BANK2        |  INP
ABC      | BANK3        |  USD

我想加入这两个表，以便在创建仪表板时我可以显示以下内容：

如果客户ABC拥有发票货币的银行账户，则显示该银行账户（在这种情况下结果将是bANK1）

如果客户没有发票货币的银行帐户，则以客户的货币显示银行帐户（在这种情况下，它将是Bank3

其他任何内容确实显示＆＃34;没有有效的银行帐户＆＃34;

当我加入我的牌桌时，它会带来多条记录......我怎样才能实现这个目标？

Answer 1

让我们拨打您的两个表customer_invoices和customer_accounts。

您可以对两个 LEFT JOIN使用以下查询（因此，如果没有银行帐户，我们仍会保留左侧数据，还有一个GROUP BY（以防万一）有人拥有一个以上某种货币的银行账户，我们不会显示所有这些账户）：

SELECT
    customer_invoices.customer, 
    customer_invoices.seller_currency, 
    customer_invoices.invoice_number, 
    customer_invoices.invoice_currency,
    coalesce( min(account_invoice_currency.bank_account), 
              min(account_seller_currency.bank_account), 
              'no valid bank account') AS chosen_bank_account
FROM
    customer_invoices
    LEFT JOIN customer_accounts AS account_seller_currency 
        ON     account_seller_currency.customer = customer_invoices.customer
           AND account_seller_currency.currency = customer_invoices.seller_currency
    LEFT JOIN customer_accounts AS account_invoice_currency
        ON     account_invoice_currency.customer = customer_invoices.customer
           AND account_invoice_currency.currency = customer_invoices.invoice_currency
GROUP BY
    customer_invoices.customer, customer_invoices.seller_currency,
    customer_invoices.invoice_number, customer_invoices.invoice_currency ;

你会得到：

customer | seller_currency | invoice_number | invoice_currency | chosen_bank_account
:------- | :-------------- | -------------: | :--------------- | :------------------
ABC      | USD             |            123 | MXP              | BANK1

您可以在 dbfiddle here

中查看整个设置

参考文献：

加入两个表 - 在两个不同的条件下过滤

1 个答案: