动态实现Scd Type2

编程问答 2022-08-14

问题描述

大家好，我想使用databricks和deltalake实现scd type 2。但是我希望代码是动态的。说有n个表，所以我不应该重写代码。

示例 这里的客户是增量表，更新是记录的更新表。现在，如果有不同的文件，则代码应该是动态的。

MERGE INTO customers
USING (
   -- These rows will either UPDATE the current addresses of existing customers or INSERT the new addresses of new customers
  SELECT updates.customerId as mergeKey,updates.*
  FROM updates
  
  UNION ALL
  
  -- These rows will INSERT new addresses of existing customers 
  -- Setting the mergeKey to NULL forces these rows to NOT MATCH and be INSERTed.
  SELECT NULL as mergeKey,updates.*
  FROM updates JOIN customers
  ON updates.customerid = customers.customerid 
  WHERE customers.current = true AND updates.address <> customers.address 
  
) staged_updates
ON customers.customerId = mergeKey
WHEN MATCHED AND customers.current = true AND customers.address <> staged_updates.address THEN  
  UPDATE SET current = false,endDate = staged_updates.effectiveDate    -- Set current to false and endDate to source's effective date.
WHEN NOT MATCHED THEN 
  INSERT(customerid,address,current,effectivedate,enddate) 
  VALUES(staged_updates.customerId,staged_updates.address,true,staged_updates.effectiveDate,null) -- Set current to true along with the new address and its effective date.

解决方法

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