SCD is abbreviation of Slowly changing dimensions. SCD applies to cases where the attribute for a record varies over time.
There are three different types of SCD.
1) SCD1 : The new record replaces the original record. Only one record exist in database – current data.
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2) SCD2 : A new record is added into the customer dimension table. Two records exist in database – current data and previous history data.
3) SCD3 : The original data is modified to include new data. One record exist in database – new information are attached with old information in same row.
(Read more here http://bit.ly/sql-interview)
3) SCD3 : The original data is modified to include new data. One record exist in database – new information are attached with old information in same row.
(Read more here http://bit.ly/sql-interview)
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