Here is the next in my series of posts explaining how common tasks in DTS can now be implemented in SSIS.
Implicitly converting between data types
In DTS it was possible to implicitly cast values from one type to another. While this seemed like a useful "feature" it was actually fraught with complications as all DTS would do was basically guess how it should do the conversion - this could result in erroneous conversions where data accuracy was compromised.
A common example of implicitly convertion is going from unicode to non-unicode. In DTS this conversion would not raise any errors but it could cause a far greater problem of data inaccuracy which might not be noticed until a much later date.
SSIS makes no such provisions for implicit conversions. Instead, SSIS will (depending on the severity) raise warnings or errors if an implicit conversion is attempted. This is both a help and a hinderance. A help because it reduces the possibility of producing inaccurate data. A hinderance because it means you, as a SSIS developer, have more work to do.
A common complaint of SSIS is that the import wizard in SQL Server Management Studio is no longer as effective because it doesn't work as well as it used to. Often this is because the import wizard does not know how to convert between one data type and another. Most commonly again, the example given before about conversion from unicode to non-unicode is cited.