In the Type 4 example, I see that you have a "ValidFrom" column in Client_SCD4_History. But it never gets populated, since Client_SCD1 doesn't have a ValidFrom date.

I see you are populating the ValidTo date in the type 4 history table, which is good.

Presumably, if you're using Type 4, all records in the main table (Client_SCD1) are "currently" valid. It would be nice to see the code that populates the ValidFrom date in the Type 4 history table. But since you're doing Type 4 based on what the Type 1 table needs, plus the history table, you haven't kept the ValidFrom date from the last time the record was updated. The Type 1 table doesn't have it.

Am I right that there's something missing here?

David Walker