SQL Server：比較兩個或多個表中的值

Question

我必須編寫一個查詢來比較兩個系統（系統A和系統B）之間的數據。在最終輸出表中，我應該具有SystemA_Field ， SystemB_Field后跟SystemA_Value ， SystemB_Value （請參見下文）。

這會將來自兩個系統的值與兩個系統的列名進行比較。

換句話說，列必須與列值一起位於行中。

Answer 1

內部查詢的結果有什么問題？

     SELECT     
         ContractType, 
         LeaseType,
         ContractNo,  
         ContractNumber
     FROM         
         TableOne INNER JOIN 
         TableA ON 
         ContractNo = ContractNumber
     WHERE     
         ContractNo = 101 

Answer 2

您不需要輸出ContractNo和ContractNumber，因為它們必須始終匹配：

SELECT t1.ContractNo, t2.ContractNumber,
CASE 
    WHEN t1.ContractType != t2.LeaseType THEN 'ContractType' 
    WHEN t1.[Address] != t2.AddressMain THEN 'Address' 
    ELSE 'N/A' END as SystemA_Field,
CASE 
    WHEN t1.ContractType != t2.LeaseType THEN 'LeaseType' 
    WHEN t1.[Address] != t2.AddressMain THEN 'AddressMain' 
    ELSE 'N/A' END as SystemB_Field,
CASE 
    WHEN t1.ContractType != t2.LeaseType THEN CAST(ContractType as VARCHAR)
    WHEN t1.[Address] != t2.AddressMain THEN CAST(Address as VARCHAR)
    ELSE 'N/A' END as SystemA_Value,
CASE 
    WHEN t1.ContractType != t2.LeaseType THEN CAST(LeaseType as VARCHAR)
    WHEN t1.[Address] != t2.AddressMain THEN CAST(AddressMain as VARCHAR)
    ELSE 'N/A' END as SystemB_Value
FROM Table1 as t1 
INNER JOIN Table2 as t2
ON t1.ContractNo = t2.ContractNumber
WHERE t1.ContractType != t2.LeaseType
OR t1.[Address] != t2.AddressMain

順便說一句，您是否看過Redgate的SQL比較？ http://www.red-gate.com/products/sql-development/sql-comparison-sdk/