Question

我正在尝试更新发票表的每一行以保存该发票的税额。这是通过获取与供应商关联的税收百分比并将其乘以发票金额（显然）得出的。我的问题是我试图用来自与其他表连接的同一表中的数据更新表。目前，我的查询显示如下：

Error Code: 1093. Table 'tblVendorInvoices' is specified twice, both as a target for 'UPDATE' and as a separate source for data

当我删除WHERE语句时

Error Code: 1054. Unknown column 'a.VENDORINVOICEID' in 'where clause'

使用WHERE。

这是我的查询：

UPDATE tblVendorInvoices SET VdrTaxAmount = 
(SELECT round(VdrInvoiceAmount*TaxAmount,2) FROM tblVendorInvoices a
LEFT JOIN tblVendors ON a.VendorName = tblVendors.VendorID
LEFT JOIN tblTax on tblVendors.vdrtaxid = tblTax.TAXID)
WHERE a.VENDORINVOICEID = tblVendorInvoices.VENDORINVOICEID;

Answer 1

这应该有效

UPDATE tblVendorInvoices SET VdrTaxAmount = c.Amount
from
(SELECT VENDORINVOICEID,round(VdrInvoiceAmount*TaxAmount,2) Amount FROM tblVendorInvoices a
LEFT JOIN tblVendors ON a.VendorName = tblVendors.VendorID
LEFT JOIN tblTax on tblVendors.vdrtaxid = tblTax.TAXID)c
WHERE c.VENDORINVOICEID = tblVendorInvoices.VENDORINVOICEID;

Answer 2

在MySQL中，使用相关子查询。我认为这是您想要的逻辑：

UPDATE tblVendorInvoices i
    SET VdrTaxAmount = 
        (SELECT round(VdrInvoiceAmount*TaxAmount,2)
         FROM tblVendors v JOIN
              tblTax t
              ON v.vdrtaxid = t.TAXID
         WHERE i.VendorID = v.VendorID
        );

Answer 3

尝试一下

UPDATE tblVendorInvoices SET VdrTaxAmount = 
(SELECT round(VdrInvoiceAmount*TaxAmount,2) 
FROM tblVendorInvoices as A
LEFT JOIN tblVendors as V ON a.VendorName = V.VendorID
LEFT JOIN tblTax on V.vdrtaxid = tblTax.TAXID)
WHERE A.VENDORINVOICEID = V.VENDORINVOICEID;

您收到该错误，是因为您没有在where语句中区分要使用的表和列：其中a.VENDORINVOICEID = tblVendorInvoices.VENDORINVOICEID; 您正在使用相同的表和列。您可能还会查看第一个join语句，因为您可能正在尝试连接字符串和INT，但这将无法正常工作。您需要联接两个具有相同数据类型的列。我不知道您的每一列都有什么类型的数据。

如何基于来自同一表的数据更新表列（使用联接）

3 个答案: