Difference between Transactional and Reporting Database

A fr开发者_高级运维iend commented like this:

I'd recommend separating out your transactional data and your reporting data into a separate database

And another one told me:

I would implement an E-R schema in the transactional data and a star schema for the reporting database

Can anyone make both clear for me? I ask, because I really didn't get difference?

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This is a transactional database: A transactional database is a DBMS where write operations on the database are able to be rolled back if they are not completed properly.

If a transactional database system loses electrical power half-way through a transaction, the partially completed transaction will be rolled back and the database will be restored to the state it was in before the transaction started.

This is a reporting database: A database used by reporting applications. Reporting databases are often duplicates of transaction databases used to off-load report processing from transaction databases.