A package is executable and acts like an application. One of the basic requirements in every application is to work with variables. SSIS has the following two types of variables:
Expressions as we have talked about them till now are a way to provide calculations and write logic in basic semi-functional expressions. The use of expressions is not limited to Derived Column or Conditional Split transforms, but they are widely used throughout the package. Expressions provide a method of setting property values dynamically, so using expressions is a way to dynamism in SSIS.
There are different types of dynamism. Control Flow Tasks can work with dynamic properties, for example attachments of a Send Mail Task can be set dynamically based on a variable value or an expression. There is a common...