Lesson 2-2: Add and configure the Foreach Loop container
Applies to: 
SQL Server
SSIS Integration Runtime in Azure Data Factory
In this task, you add the ability to loop through a folder of flat files and apply Lesson 1's data flow transformation to each of those flat files. You do this by adding and configuring a Foreach Loop container to the control flow.
The Foreach Loop container that you add must be able to connect to each flat file in the folder. Because all the files in the folder have the same format, the Foreach Loop container can use the same Flat File connection manager to connect to each of these files. The Flat File connection manager that the container uses is the one you created in Lesson 1.
Currently, the Flat File connection manager from Lesson 1 connects to only one specific flat file. To iteratively connect to each flat file in the folder, you have to configure both the Foreach Loop container and the Flat File connection manager as follows:
Foreach Loop container: You map the enumerated value of the container to a user-defined package variable. The container then uses this variable to dynamically modify the ConnectionString property of the Flat File connection manager and iteratively connect to each flat file in the folder.
Flat File connection manager: You modify the connection manager that was created in Lesson 1 by using a user-defined variable to populate the connection manager's ConnectionString property.
The procedures in this task show you how to create and modify the Foreach Loop container to use a user-defined package variable, and to add the data flow task into the loop. You'll learn how to modify the Flat File connection manager to use that user-defined variable in the next task.
After you have made these modifications to the package, when the package is run, the Foreach Loop Container iterates through all files in the Sample Data folder. Each time a file is found that matches the criterion, the Foreach Loop Container populates the new variable with the file name, maps that variable to the ConnectionString property of the Sample Currency Data Flat File connection manager, and then runs the data flow against that file. In this way, each iteration of the Foreach Loop the Data Flow task consumes a different flat file.
Note
Because Microsoft Integration Services separates control flow from data flow, any looping that you add to the control flow won't require modification to the data flow. Therefore, the Lesson 1 data flow does not have to be changed.
Add a Foreach Loop container
In SQL Server Data Tools, select the Control Flow tab.
In the SSIS Toolbox, expand Containers, and then drag a Foreach Loop Container onto the design surface of the Control Flow tab.
Right-click the new Foreach Loop Container and select Edit.
In the Foreach Loop Editor dialog, on the General page, for Name, enter Foreach File in Folder. Select OK.
Right-click the Foreach Loop container, select Properties, and in the Properties window verify that the LocaleID property is set to English (United States).
Configure the enumerator for the Foreach Loop container
Double-click Foreach File in Folder to reopen the Foreach Loop Editor.
Select Collection.
On the Collection page, select Foreach File Enumerator.
In the Enumerator configuration group, select Browse.
In the Browse for Folder dialog box, locate the folder on your machine that contains the Currency_*.txt files included with the sample data.
In the Files box, enter Currency_*.txt.
Map the enumerator to a user-defined variable
Select Variable Mappings.
On the Variable Mappings page, in the Variable column, select the empty cell and select <New Variable...>.
In the Add Variable dialog box, for Name enter varFileName.
Note
Variable names are case-sensitive.
Select OK.
Select OK again to exit the Foreach Loop Editor dialog.
Add the data flow task to the loop
- Drag the Extract Sample Currency Data data flow task onto the Foreach File in Folder Foreach Loop container.
Go to next task
Step 3: Modify the Flat File connection manager
See also
Configure a Foreach Loop container
Use variables in packages