In SSIS (SQL Server Integration Services), the Derived Column transformation is a powerful tool that allows us to manipulate data within our data flow. One common task we may need to perform is converting the data type of a column. In this tutorial, we will explore how to use the Derived Column transformation in SSIS to convert data types.
What is the Derived Column Transformation?
The Derived Column transformation in SSIS provides us with a flexible way to add, modify, or remove columns in our data flow. It allows us to perform various operations on existing columns and create new derived columns based on expressions.
Converting Data Types using the Derived Column Transformation
To convert a data type using the Derived Column transformation, follow these steps:
Step 1: Add a Derived Column Transformation
To get started, drag and drop the Derived Column transformation from the SSIS toolbox onto the Data Flow canvas.
Step 2: Configure the Derived Column Transformation
Select the Derived Column transformation on the canvas and open its editor by double-clicking on it. In the editor, you will find two sections: Input Columns and Derived Columns.
- This section lists all available input columns from your data source.
- Select the column you want to convert from this list.
- This section allows you to define new derived columns or modify existing ones.
- Type a name for your new derived column in the “Derived Column” field.
- Specify the expression to convert the data type in the “Expression” field.
- Choose the desired data type for your derived column from the “Data Type” dropdown.
Step 3: Define the Expression
In the “Expression” field, you can use various functions and operators to perform the conversion. Here are a few examples:
- To convert a string column to an integer, use the expression: (DT_I4) [YourColumnName]
- To convert an integer column to a string, use the expression: (DT_WSTR, length) [YourColumnName]
- To convert a date column to a string, use the expression: (DT_WSTR, length) (DT_DBDATE) [YourColumnName]
Note that you need to replace [YourColumnName] with the actual name of your column and specify the appropriate length for string conversions.
Step 4: Map Output Columns
After defining your derived columns and expressions, click on the “OK” button in the Derived Column Transformation Editor. The editor will close, and you will return to the Data Flow canvas.
Next, connect your Derived Column transformation to another component in your data flow (e.g., Destination or another transformation). Make sure to map any output columns from your Derived Column transformation as needed.
The Derived Column transformation in SSIS provides us with a flexible way to manipulate our data. By using this transformation along with expressions, we can easily convert data types within our data flow. Whether we need to convert strings to integers or dates to strings, SSIS offers us the tools to accomplish these tasks efficiently.
With the steps outlined in this tutorial, you can confidently utilize the Derived Column transformation in SSIS to convert data types and ensure your data is processed correctly.