Database Reference
In-Depth Information
Outlining a Data Flow Task
Data flow tasks require at least one data source component and one data destination component. Often you just
need one of each, but you can have more than one data source and more than one data destination per data flow.
To outline your Data Flow task steps, begin by placing data source and data destination components from
the Toolbox onto the designer surface (Figure
8-3
). At this point, even though it is possible to connect them with
arrows between each of the components, do not do so! Adding arrows before configuring the components causes
problems. The arrows of the data flow do not work the same as the arrows on the Control Flow tab. Control flow
arrows represent a precedent constraint and control the order of execution.
Data flow arrows represent a data flow path and pass metadata from the component at the arrow's origin
to the component at the end of the arrow. If arrows are connected between components before the source
component is configured, there will be no metadata to pass on to the end component. Therefore, connect the
arrows only
after
each source component is configured.
Figure 8-3.
Outlining a data flow task should not include a data flow path
Configuring the Data Source
A data source component is the heart of each data flow task. You can add a data source component to the data
flow by clicking the SSIS Toolbox and locating either the Source Assistant or one of the data source component lists
under the Other Sources category. Selecting the Source Assistant will launch a wizard that helps you select one of
the other sources. Therefore, you will not need to use it when you already know which type of component you want.
You should always choose the data source and destination components to match the connection manager
objects in your SSIS package. We are using OLE DB connections in our SSIS package; therefore, we want to use an
OLE DB Source component.
When you click a component, you will see data path arrows displayed, but remember that until the
component is properly configured, you cannot use them to connect to other components. A data source
component is configured by right-clicking the component and choosing Edit from the context menu.
