Basically, data coming from the source is transformed before being
loaded to the destination.
Data Source Components
Since extraction of data is one of the operations needed for ETL, SSIS is equipped
with a rich interface for retrieving or merging data from heterogeneous data stores.
The variety of data sources that SSIS can connect to is rather large, using .NET,
OLEDB, and ODBC data access methods. While .NET and OLEDB access methods
are used for connecting to relational data, ODBC data access is used for legacy data.
The ODBC data access method is especially useful, because there are ODBC drivers
for practically every kind of database product. In addition to this, SSIS can also
leverage data from flat files, XML files, MS Excel spread sheet files, and use MSOLAP
provider, to access Analysis Services. The following figure shows various options for
data source components available in the Visual Studio 2005 IDE (Standard Edition).
It should be mentioned that the DataReader Source, a component of the .NET Data
Access Strategy, connects to many of the vendors thorough the optimized
.NET provider.
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Chapter 1
[ 13 ]
Of the available Data Flow Sources, the following are used in this book:
DataReader Source
Excel Source
OLE DB Source
While .NET data providers were developed recently, OLEDB and ODBC have
existed for a considerable amount of time and there exists a large number of both
Microsoft and non-Microsoft products for establishing connectivity.
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