从重复记录中获取第一条记录并在其他表中使用其标识

Question

我有两个临时表，其中有重复项。两个表包含如下记录。

DECLARE @TempCompany TABLE (TempCompanyCode VARCHAR(100), TempCompanyName VARCHAR(100))
INSERT INTO @TempCompany VALUES ('00516','Company1')
INSERT INTO @TempCompany VALUES ('00135','Company1')
INSERT INTO @TempCompany VALUES ('00324','Company2')
INSERT INTO @TempCompany VALUES ('00566','Company2')
SELECT * FROM @TempCompany 

DECLARE @TempProduct TABLE (TempProductCode VARCHAR(100), TempProductName VARCHAR(100), TempCompanyCode VARCHAR(100))
INSERT INTO @TempProduct VALUES ('001000279','Product1','00516')
INSERT INTO @TempProduct VALUES ('001000279','Product1','00135')
INSERT INTO @TempProduct VALUES ('001000300','Product2','00135')
INSERT INTO @TempProduct VALUES ('001000278','Product3','00566')
INSERT INTO @TempProduct VALUES ('001000278','Product3','00324')
INSERT INTO @TempProduct VALUES ('001000304','Product4','00566')
SELECT * FROM @TempProduct

Company 是主表，product 是子表。产品包含公司的参考。现在这些是我的临时表，我需要将这些表中的正确值插入到我的主表中。

我想插入如下记录

DECLARE @Company TABLE(CompanyID INT IDENTITY(1,1), CompanyCode VARCHAR(100), CompanyName VARCHAR(100))
INSERT INTO @Company VALUES ('00516','Company1')
DECLARE @IDOf00516 INT = @@IDENTITY
INSERT INTO @Company VALUES ('00324','Company2')
DECLARE @IDOf00324 INT = @@IDENTITY
SELECT * FROM @Company 

DECLARE @Product TABLE(ProductID INT IDENTITY(1,1), ProductCode VARCHAR(100), ProductName VARCHAR(100), CompanyID INT)
INSERT INTO @Product VALUES ('001000279','Product1',@IDOf00516)
INSERT INTO @Product VALUES ('001000300','Product2',@IDOf00516)
INSERT INTO @Product VALUES ('001000278','Product3',@IDOf00324)
INSERT INTO @Product VALUES ('001000300','Product4',@IDOf00324)
SELECT * FROM @Product

我附上了以下图片，了解它在运行查询时的外观。

有人可以帮忙吗？

Answer 1

我可能会先将唯一记录从 tempCompany 插入 Company 表，然后从 TempProduct 插入并查找插入的 Company 表。

即首先插入公司：

INSERT INTO @Company (CompanyCode, CompanyName)
SELECT temp.TempCompanyCode, temp.TempCompanyName 
FROM @TempCompany AS temp

然后使用连接插入产品以查找 companyid：

INSERT INTO @Product (ProductCode, ProductName, CompanyId)
SELECT temp.TempProductCode, temp.TempProductName, c.CompanyID
FROM @TempProduct AS temp
    JOIN @Company AS c ON temp.TempCompanyCode = c.CompanyCode -- Lookup to find CompanyID

但是这并没有考虑到重复和主表已经插入记录的可能性。 添加重复并检查已经存在的记录，最终结果可能如下所示：

--1. insert records not already in company table:
INSERT INTO @Company (CompanyCode, CompanyName)
SELECT DISTINCT temp.TempCompanyCode, temp.TempCompanyName 
FROM @TempCompany AS temp
    LEFT JOIN @Company AS c ON temp.TempCompanyCode = c.CompanyCode -- Will match Companies that already exists in @Companies
WHERE c.CompanyID IS NULL -- Company does not already exist
ORDER BY temp.TempCompanyCode 

--2. insert product records:
INSERT INTO @Product (ProductCode, ProductName, CompanyId)
SELECT DISTINCT temp.TempProductCode, temp.TempProductName, c.CompanyID
FROM @TempProduct AS temp
    JOIN @Company AS c ON temp.TempCompanyCode = c.CompanyCode -- Lookup to find CompanyID
    LEFT JOIN @Product AS p ON temp.TempProductCode = p.ProductCode AND temp.TempCompanyCode = c.CompanyCode -- Will match products that already exists in @Products
WHERE p.ProductID IS NULL -- Product does not already exists
ORDER BY c.CompanyID, temp.TempProductCode

--3. Check result
SELECT * FROM @Company
SELECT * FROM @Product

请注意，我使用 LEFT JOIN 并添加 WHERE 条件来检查记录是否已存在于您的主表中。 使用MERGE 语句可以很好地实现这一点 - 但我习惯于可读性稍差的 LEFT JOIN/WHERE 方法:)

编辑

只有 TempCompanyName 用于确定 TempCompany 中的行是否唯一。 IE。公司代码为 00135 的 Company1 应不插入。

为此，我将利用ROW_NUMBER 帮助查找要插入的公司行。我已向 @TempCompany 添加了一个标识列，以确保插入的第一行将是所使用的行（即确保 00516 用于 Company1 而不是 00135）。

新的@TempCompany 定义：

DECLARE @TempCompany TABLE (TempCompanyId INT IDENTITY(1,1), TempCompanyCode VARCHAR(100), TempCompanyName VARCHAR(100))

更新的脚本添加了 row_number，并通过 TempCompany（名称）从 Product 额外加入到 Company。额外的连接是为了正确处理具有 CompanyCode 00516 和 CompanyCode 00135 的 Product1：

--1. insert records not already in company table:
;WITH OrderedTempCompanyRows AS (SELECT ROW_NUMBER() OVER (PARTITION BY TempCompanyName ORDER BY TempCompanyId) AS RowNo, TempCompanyCode, TempCompanyName FROM @TempCompany)
INSERT INTO @Company (CompanyCode, CompanyName)
SELECT DISTINCT temp.TempCompanyCode, temp.TempCompanyName 
FROM OrderedTempCompanyRows temp
    LEFT JOIN @Company AS c ON temp.TempCompanyName = c.CompanyName -- Will match Companies that already exists in @Companies
WHERE temp.RowNo = 1 -- Only first company according to row_number
    AND c.CompanyID IS NULL -- Company does not already exist
ORDER BY temp.TempCompanyName 

--2. insert product records:
INSERT INTO @Product (ProductCode, ProductName, CompanyId)
SELECT DISTINCT temp.TempProductCode, temp.TempProductName, c.CompanyID
FROM @TempProduct AS temp
    JOIN @TempCompany tc ON temp.TempCompanyCode = tc.TempCompanyCode -- Find Companyname in @Tempcompany table
    JOIN @Company AS c ON tc.TempCompanyName = c.CompanyName -- Join to @Company on Companyname to find CompanyID
    LEFT JOIN @Product AS p ON temp.TempProductCode = p.ProductCode AND temp.TempCompanyCode = c.CompanyCode -- Will match products that already exists in @Products
WHERE p.ProductID IS NULL -- Product does not already exists
ORDER BY c.CompanyID, temp.TempProductName

--3. Check result
SELECT * FROM @Company
SELECT * FROM @Product