# Use an Expression in a Data Flow Component

Applies To: SQL Server 2016

This procedure describes how to add an expression to the Conditional Split transformation or to the Derived Column transformation. The Conditional Split transformation uses expressions to define the conditions that direct data rows to a transformation output, and the Derived Column transformation uses expressions to define values assigned to columns.

To implement an expression in a transformation, the package must already include at least one Data Flow task and a source. For information about adding items to packages, see the following topics:

### To create an expression

In SQL Server Data Tools (SSDT), open the Integration Services project that contains the package you want.

In Solution Explorer, double-click the package to open it.

In SSIS Designer, click the

**Control Flow**tab, and then click the Data Flow task that contains the data flow in which you want to implement an expression.Click the

**Data Flow**tab, and drag either a Conditional Split or Derived Column transformation from the**Toolbox**to the design surface.Drag the green connector from the source or a transformation to the Conditional Split or Derived Column transformation.

Double-click the transformation to open its dialog box.

In the left pane, expand

**Variables**to display system and user-defined variables, and expand**Columns**to display the transformation input columns.In the right pane, expand

**Mathematical Functions**,**String Functions**,**Date/Time Functions**,**NULL Functions**,**Type Casts**, and**Operators**to access the functions, the casts, and the operators that the expression grammar provides.Depending on the transformation, do one of the following to build an expression:

In the

**Conditional Split Transformation Editor**dialog box, drag variables, columns, functions, operators, and casts to the**Condition**column. Alternatively, you can type an expression directly in the**Condition**column.In the

**Derived Column Transformation Editor**dialog box, drag variables, columns, functions, operators, and casts to the**Expression**column. Alternatively, you can type an expression directly in the**Expression**column.Note

When you remove the focus from the**Condition**column or the**Expression**column, the expression text might be highlighted to indicate that the expression syntax is incorrect.

Click

**OK**to exit the dialog box.Note

If the expression is not valid, an alert appears describing the syntax errors in the expression.

## See Also

Integration Services (SSIS) Expressions

Conditional Split Transformation

Derived Column Transformation

Data Flow Task

Data Flow