Data warehouse

one example which could make this term clear, suppose a engineering student collects notes from
various sources like libaray books ,class notes, friends notes etc
and then make a perfect copy of it from which he could get the whole concept,
which will help him making the understanding of concept .

here the integration of all the notes from various sources can be thought of as data warehouse

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The storage area for processed and integrated data across different sources
which can be operational data or external data
A data ware house allows its users to extract required data,for business analysis
and strategic decision making


conceptualy:A data warehouse is a home for 'second hand' data that originates
in either other corporate applications,or some data source externa;
to your comany

Formaly:A data ware house is a stand alone repositoy of information,integrated from several,
possibaly heterogeneous operational databases.



definition by Ralph Kimball :
A warehouse is a copy of transaction data specifically
structured for query and analyisis.
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Chatrasal's def
dataware house is data collected from different source databases,data marts, reports,etc.
which are summarized and maintained in multidimensional form .