Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

SQL Ser ver Integration Ser vices (SSIS)
Your friend and mine — that’s what SSIS (formerly known as Data Transformation Services or DTS) is. I
simply sit back in amazement every time I look at this feature of SQL Server. To give you a touch of perspective
here, I’ve done a couple of Decision Support Systems (DSS) projects over the years. (These are
usually systems that don’t have online data going in and out, but instead pull data together to help management
make decisions.) A DSS project gathers data from a variety of sources and pumps it into one
centralized database to be used for centralized reporting.
These projects can get very expensive very quickly, as they attempt to deal with the fact that not every
system calls what is essentially the same data by the same name. There can be an infinite number of issues
to be dealt with. These can include data integrity (what if the field has a NULL and we don’t allow NULLs?)
or differences in business rules (one system deals with credits by allowing a negative order quantity,
another doesn’t allow this and has a separate set of tables to deal with credits). The list can go on and
on, and so can the expense.
With SSIS a tremendous amount of the coding, usually in some client-side language, that had to be done
to handle these situations can be eliminated or, at least, simplified. SSIS enables you to take data from
any data source that has an OLE DB or .NET data provider and pump it into a SQL Server table.
Be aware that there is a special OLE DB provider for ODBC. This provider allows
you to map your OLE DB access directly to an ODBC driver. That means anything
that ODBC can access can also be accessed by OLE DB (and, therefore, SSIS).
While we’re at it, it’s also worth pointing out that SSIS, although part of SQL Server,
can work against any OLE DB source and any OLE DB destination. That means that
SQL Server doesn’t need to be involved in the process at all other than to provide
the data pump. You could, for example, push data from Oracle to Excel, or even DB/2
to MySQL.
While transferring your data, we can also apply what are referred to as transformations to that data.
Transformations essentially alter the data according to some logical rule(s). The alteration can be as simple
as changing a column name, or as complex as an analysis of the integrity of the data and application
of rules to change it if necessary. To think about how this is applied, consider the example I gave earlier of
taking data from a field that allows NULLs and moving it to a table that doesn’t allow NULLs. With SSIS
you can automatically change any NULL values to some other value you choose during the transfer process.
(For a number, that might be zero or, for a character, it might be something like unknown.)
Bulk Copy Program (bcp)
Chapter 2: Tools of the Trade
If SSIS is your friend and mine, then the Bulk Copy Program, or bcp, would be that old friend that we may
not see that much anymore, but really appreciate when we do.
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