DW - SCD - Slowly changing dimensions

Dimension - in data management & data warehousing - logical grouping of data
[geographical location, customer , product]
Type 0 - Values remain as they were at the time the dimension record was first inserted. [ history ]
Type I - This methodology overwrites old with new data, and therefore does not track historical data.
Supplier_Key Supplier_Code Supplier_Name Supplier_State
123         ABC xyz                               CA
Supplier_Code is the natural key.
Supplier_Key is a surrogate key ( joins use integer rather than character keys.)
Type II:This method tracks historical data by creating multiple records for a given natural key in the dimensional tables with separate surrogate keys and/or different version numbers.
Start_Date,End_Date( null - current one)
Type IV:Is usually referred to as using "history tables".Where one table keeps the current data, and an additional table is used to keep a record of some or all changes.

Slowly_changing_dimension