Hallo Klaus ,
i know what you explain but my question was right. Because we want to Map between physical and logical Data Models in this way.
SDM : Source Data Model = physical Representation of Tables/Views
BDM : Business Data Model = logical or conceptional Representation of a Business Model
CDM: Common Data Model = Physical Data Model derived or mapped from BDM
(you explain me this part a derivation from BDM into a CDM
and yes this is correct and usefull but ... )
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we need this mappings
SDM =dmm=> BDM =dmm=> CDM
because BDM and PDM must not have the same "Structure" one could be in 3 NF and the other
a Data Vault or Star/Snowflak etc..
I know i could derive from BDM (ldm) into a 1:1 "pdm and than i could use in the standard way DMM´s
but we want to avoid additional transformations as much as possible because the mapping chain will grow with each.
br thomas