Sql 我正在尝试在access查询中查找重复项而不删除

我正试图在access中建立一个表达式。如果商品代码和发票号重复，我需要某种标志。我希望该栏显示-1

ItemCode    UnitPrice   InvoiceNo
R50         18.60       0446394
R50         18.60       0446395
R64         20.60       0444965
R64         20.60       0444965
R64         22.60       0446394
R64         22.60       0446394
G32         24.60       0445689

你能帮忙吗？ 下面是我用来获取这些结果的sql

选择[Amerinet sales].[sales person]，[Amerinet sales].ShipToName[Amerinet sales].ShipToAddress1[Amerinet sales].ShipToAddress2[Amerinet sales].ShipToAddress3[Amerinet sales].ShipToCity[Amerinet sales].ShipToZipCode[Amerinet sales].ItemCode[Amerinet sales].UnitPrice[Amerinet sales].QuantityShipped，[Amerinet sales].ExtensionAmt[Amerinet sales].InvoiceDate[Amerinet sales].InvoiceNo[Amerinet sales].Totals[Amerinet sales].BillToName[Amerinet sales].BillToAddress1[Amerinet sales].BillToAddress2[Amerinet sales].BillToAddress3[Amerinet sales].BillToCity[Amerinet sales].BillToState[Amerinet sales].BillToZipCode[Amerinet Match][sales person]，[Amerinet Match]。ShipToName[Amerinet Match]。ShipToAddress1[Amerinet Match]。ShipToAddress2[Amerinet Match]。ShipToAddress3[Amerinet Match]。ShipToCity[Amerinet Match]。ShipToState[Amerinet Match]。ShipToZipCode[Amerinet Match]。项目代码[Amerinet Match]。单价[Amerinet Match]。数量[Amerinet Match].ExtensionAmt[Amerinet Match].InvoiceDate[Amerinet Match].InvoiceNo[Amerinet Match].Totals[Amerinet Match].BillToAddress1[Amerinet Match].BillToAddress2[Amerinet Match].BillToAddress3[Amerinet Match].BillToState[Amerinet Match].BillToZipCode[Amerinet Match].[GPO ID]，[Amerinet Match].GLN[Amerinet Match].Field3[Amerinet Match].[DEA]，[Amerinet Match].[Name 1]，[Amerinet Match].[Address 1]，[Amerinet Match].[Amerinet Match].[State/Province]，[Amerinet Match].[Name 2]，[Amerinet Match].[Address 2]，[Amerinet Match].[Address 3]，[Amerinet Match].国家[Amerinet Match].电话[Amerinet Match].传真[Amerinet Match].Field17[Amerinet Match].Field18[Amerinet Match].[Direct Parent GPO ID]，[Amerinet Match].[Direct Parent Name 1]，[Amerinet Match].[Top Parent Name 1]，[Amerinet Match].Field23[Amerinet Match].Field24[Amerinet Match].Field25[Amerinet Match].[Class of Trade]，[Amerinet Match].Field27[Amerinet Match].Field28[Amerinet Match].Field29[Amerinet Match].Field30[Amerinet Match].Field31[Amerinet Match].Field32[Amerinet Match].Field33[Amerinet Match].Field34[Amerinet Match].[Sub Class]，[Amerinet Match].Alliance[Amerinet Match].IDN[Amerinet Match]。[唯一来源Mbr Y/N]，[Amerinet匹配][床数] 从[Amerinet sales]左加入[Amerinet sales]上的[Amerinet Match]。项目代码=[Amerinet Match]。项目代码和[Amerinet sales]。发票编号=[Amerinet Match]。发票编号 按[Amerinet sales].[sales person]，[Amerinet sales].ShipToName[Amerinet sales].ShipToAddress1[Amerinet sales].ShipToAddress2[Amerinet sales].ShipToAddress3[Amerinet sales].ShipToCity[Amerinet sales].ShipToState[Amerinet sales].ShipToZipCode[Amerinet sales].ItemCode[Amerinet sales].UnitPrice[Amerinet sales].QuantityShipped[Amerinet sales].ExtensionAmt[Amerinet sales].InvoiceDate[Amerinet sales].InvoiceNo[Amerinet sales].Totals[Amerinet sales].BillToAddress1[Amerinet sales].BillToAddress2[Amerinet sales].BillToAddress3[Amerinet sales].BillToCity[Amerinet sales].BillToState[Amerinet sales].BillToZipCode[Amerinet Match]。[sales person]，[Amerinet Match]。ShipToName[Amerinet Match]。ShipToAddress1[Amerinet Match]。ShipToAddress2[Amerinet Match]。ShipToAddress3[Amerinet Match]。ShipToCity[Amerinet Match]。ShipToState[Amerinet Match]。ShipToZipCode[Amerinet Match]。项目代码[Amerinet Match]。单价[Amerinet Match].QuantityShipped[Amerinet Match].ExtensionAmt[Amerinet Match].InvoiceDate[Amerinet Match].InvoiceNo[Amerinet Match].Totals[Amerinet Match].BillToAddress1[Amerinet Match].BillToAddress2[Amerinet Match].BillToAddress3[Amerinet Match].BillToCity[Amerinet Match].BillToState[Amerinet Match].BillToZipCode[Amerinet Match].[GPO ID]，[Amerinet Match].GLN[Amerinet Match].Field3[Amerinet Match].[DEA]，[Amerinet Match].[Name 1]，[Amerinet Match].[Address 1]，[Amerinet Match].[State/Province]，[Amerinet Match].[Postal Code]，[Amerinet Match].[Name 2]，[Amerinet Match].[Address Type]，[Amerinet Match].[Address 2]，[Amerinet Match]。[Address 3]，[Amerinet Match]。国家：[Amerinet Match]。电话[Amerinet Match]。传真[Amerinet Match]。字段17[Amerinet Match]。字段18[Amerinet Match]。[Direct Parent GPO ID]，[Amerinet Match]。[Direct Parent Name 1]，[Amerinet Match]。[Top Parent GPO ID]，[Amerinet Match]。[Top Parent Name 1]，[Amerinet Match]。字段23，[Amerinet Match].Field24

---

，[Amerinet Match].Field25[Amerinet Match].[Class of Trade]，[Amerinet Match].Field27[Amerinet Match].Field28[Amerinet Match].Field29[Amerinet Match].Field30[Amerinet Match].Field31[Amerinet Match].Field32[Amerinet Match].Field33[Amerinet Match].[Sub Class]，[Amerinet Match].Alliance[Amerinet Match].IDN，[Amerinet Match]。[Sole Source Mbr Y/N]，[Amerinet Match]。[of Beds]

你想要这样的东西吗

select t.*,
       iif(cnt > 1, -1, 0) as HasDuplicate
from test as t inner join
      (select itemcode, invoiceno, count(*) as cnt
       from test as t
       group by itemcode, invoiceno
      ) as ii
      on ii.itemcode = t.itemcode and ii.invoiceno = t.invoiceno;

在添加了一个名为dupe的列之后，我使用MySQL用您的数据测试了这个查询。应该可以访问

生成以下输出

"itemCode"  "UnitPrice" "InvoiceNo" "dupe"
"R50"            "19"    "0446394"  "0"
"R50"            "19"    "0446395"  "0"
"R64"            "21"    "0444965"  "-1"
"R64"            "21"    "0444965"  "-1"
"R64"            "23"    "0446394"  "-1"
"R64"            "23"    "0446394"  "-1"
"G32"            "25"    "0445689"  "0"

---

如果只需要找出是否有重复项，最好单独查询，按项目代码和发票号分组，并将计数*作为聚合。[您是否用表名替换了表？我替换了，但我也忘了提到这是查询的结果。我已将我的查询包含在上面。您能帮我将其添加到其中吗？我忘了提到这是查询的结果。这是我用于获取上面列出的结果的查询sql。您能告诉我如何将其添加到这里吗？如果您想添加查询，请告诉我指示符列您可以在单独的查询中执行此操作。然后，您可以根据需要将isDupe列合并到上述查询的选择条件中。否则，如果您必须将此操作作为大型查询的一部分，您可以将其添加到您的FROM子句中。请澄清我的最后一条评论。如果您想添加指示符列，请在单独的u中执行此操作更新查询。然后，您可以根据需要将isDupe列合并到后续查询的选择条件中。否则，如果您必须在大型查询中执行此操作，则可以通过删除UPDATE和SET子句并将查询与结果集关联，将SELECT部分添加到FROM子句中。

"itemCode"  "UnitPrice" "InvoiceNo" "dupe"
"R50"            "19"    "0446394"  "0"
"R50"            "19"    "0446395"  "0"
"R64"            "21"    "0444965"  "-1"
"R64"            "21"    "0444965"  "-1"
"R64"            "23"    "0446394"  "-1"
"R64"            "23"    "0446394"  "-1"
"G32"            "25"    "0445689"  "0"