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

公司是主表，产品是子表。产品包含公司参考。现在这些是我的临时表，我需要从这些表中插入适当的值到我的主表。

我想按以下方式插入记录

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，了解运行查询时的外观。

有人可以帮忙吗？

Answer 1

我可能首先将tempCompany中的唯一记录插入到Company表中，然后从TempProduct执行插入操作，并查找插入的Company表。

即。第一次插入公司：

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

然后使用联接插入产品以查找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，这并未考虑重复项以及主表已插入记录的可能性。 添加重复并检查已存在的记录，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条件以检查主表中是否已存在记录。 使用MERGE语句可以很好地实现这一点 - 但我习惯于稍微不那么易读的LEFT JOIN / WHERE方法：）

修改

只有TempCompanyName用于确定TempCompany中的行是否唯一。即使用CopmpanyCode 00135的Company1应该不插入。

为实现这一目标，我将利用ROW_NUMBER帮助查找要插入的公司行。我已经在@TempCompany中添加了一个标识列，以确保插入的第一行是使用的行（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))

添加了row_number的更新脚本以及从Product到TempCompany（在名称上）到公司的额外连接。额外的连接是为了正确处理Product1与CompanyCode 00516和CompanyCode 00135：

--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