Datasheet
An example workflow can be seen in Figure 1-6. This package first copies files using the File System
task, and if that is successful and meets certain criteria in the expression, it will transform the files using
the Data Flow task. If the first step fails, then a message will be sent to the user by using the Send Mail
task. You can also see the small fx icon above the Data Flow task. This is graphically showing the
developer that this task will not execute unless an expression has also been met and the previous step
has successfully completed. The expression can check anything, such as looking at a checksum, before
running the Data Flow task.
Figure 1-6
Containers
Containers are a new concept in SSIS that didn’t previously exist in SQL Server. They are a core unit in
the SSIS architecture that help you logically group tasks together into units of work or create complex
conditions. By using containers, SSIS variables and event handlers (these will be discussed in a moment)
can be defined to have the scope of the container instead of the package. There are four types of containers
that can be employed in SSIS:
❑ Task host container: The core type of container that every task implicitly belongs to by default.
The SSIS architecture extends variables and event handlers to the task through the task host
container.
❑ Sequence container: Allows you to group tasks into logical subject areas. In BIDS, you can then
collapse or expand this container for usability.
❑ For loop container: Loops through a series of tasks for a given amount of time or until a condition
is met.
❑ For each loop container: Loops through a series of files or records in a data set and then executes
the tasks in the container for each record in the collection.
As you read through this book, you’ll gain lots of experience with the various types of containers.
Variables
Variables are one of the most powerful components of the SSIS architecture. In SQL Server 7.0 and 2000
DTS, these were called global variables, but they’ve been drastically improved on in SSIS. Variables
allow you to dynamically configure a package at runtime. Without variables, each time you wanted to
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