Add or Change a Property Expression
Applies to: 
SQL Server
SSIS Integration Runtime in Azure Data Factory
You can create property expressions for packages, tasks, Foreach Loop containers, For Loop containers, Sequence containers, event handlers, package and project level connection managers, and log providers.
To create or change property expressions, you can use either the Property Expressions Editor or Expression Builder. The Property Expressions Editor can be accessed from either the custom editors that are available for tasks and containers, or from the Properties window. Expression Builder can be accessed from inside the Property Expressions Editor. While you can write expressions in either the Property Expressions Editor or Expression Builder, Expression Builder provides a graphical set of tools that makes it simple to build complex expressions.
To learn more about the syntax, operators, and functions that Integration Services provides, see Operators (SSIS Expression) and Functions (SSIS Expression). The topic for each operator or function includes examples of using that operator or function in an expression. For examples of more complex expressions, see Use Property Expressions in Packages.
To create or change a property expression
In SQL Server Data Tools (SSDT), open the project that contains the Integration Services package you want.
In Solution Explorer, double-click the package to open it, and then do one of the following:
If the item is a task or a container, double-click the item, and then click Expressions in the editor.
Right-click the item and then click Properties.
Click in the Expressions box and then click the ellipsis (...).
In the Property Expressions Editor, select a property in the Property list, and then do one of the following:
Type or change the property expression directly in the Expression column, and then click OK.
-or-
Click the ellipsis (...) in the expression row of the property to open the Expression Builder.
(Optional) In the Expression Builder, do any of the following tasks:
To access system and user-defined variables, expand Variables.
To access the functions, the casts, and the operators that the SSIS expression language provides, expand Mathematical Functions, String Functions, Date/Time Functions, NULL Functions, Type Casts, and Operators.
To build or change an expression in the Expression Builder, drag variables, columns, functions, operators, and casts to the Expression box, or type the expression in the box.
To view the evaluation result of the expression, click Evaluate Expression in the Expression Builder.
If the expression is not valid, an alert appears that describes the syntax errors in the expression.
Note
Evaluating an expression does not assign the evaluation result to the property.
Select OK.
See Also
Integration Services (SSIS) Expressions
Use Property Expressions in Packages
Integration Services (SSIS) Packages
Integration Services Containers
Integration Services Tasks
Integration Services (SSIS) Event Handlers
Integration Services (SSIS) Connections
Integration Services (SSIS) Logging