Advanced Scripting in SSIS

Understanding Script Components

Script components in SSIS provide a way to write custom code (using C# or Visual Basic .NET) that can be integrated into your data flow. They offer unparalleled flexibility for complex data transformations, validations, and custom logic that cannot be achieved with standard SSIS transformations.

Types of Script Components:

• Script Component as Source: For creating custom data sources.
• Script Component as Transformation: For performing custom data transformations.
• Script Component as Destination: For writing data to custom destinations.

Each type has specific configuration options and events to handle data input and output.

Using the Script Task

The Script Task allows you to execute custom code at the control flow level. This is ideal for tasks such as:

• Interacting with the file system (creating directories, deleting files).
• Sending custom email notifications.
• Executing dynamic SQL commands.
• Calling external APIs or web services.
• Performing complex calculations or business logic not directly related to data flow.

You can access SSIS variables and parameters within the Script Task, making it a powerful tool for controlling package execution.

Example: Custom Data Validation with Script Component

Let's illustrate with a common scenario: validating email addresses within a data flow.

Steps:

1. Add a Data Flow Task to your control flow.
2. Inside the Data Flow Task, add a source component (e.g., OLE DB Source) and a Script Component.
3. Configure the source to read your data, including an email address column.
4. Change the Script Component type to Transformation.
5. Connect the output of your source to the Script Component.
6. In the Script Component Transformation Editor:
   • Under Input Columns, select the email address column you want to validate.
   • Under Inputs and Outputs, select Output 0 (or your output name). Add a new output column, for example, IsValidEmail (Boolean).
   • Add another output for error rows, e.g., ErrorDescription (String).
   • Go to the Script tab and click Edit Script....

Script (C#):

using System;
using System.Text.RegularExpressions;
using Microsoft.SqlServer.Dts.Pipeline.Wrapper;
using Microsoft.SqlServer.Dts.Runtime.Wrapper;

[Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute]
public class ScriptMain : UserComponent
{
    // Regular expression for basic email validation
    private const string EmailRegexPattern = @"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$";
    private Regex emailRegex;

    public override void PreExecute()
    {
        base.PreExecute();
        emailRegex = new Regex(EmailRegexPattern);
    }

    public override void Input0_ProcessInputRow(Input0Buffer Row)
    {
        bool isValid = false;
        string errorMessage = string.Empty;

        if (!Row.EmailAddress_IsNull)
        {
            string email = Row.EmailAddress;
            if (emailRegex.IsMatch(email))
            {
                isValid = true;
            }
            else
            {
                errorMessage = "Invalid email format";
            }
        }
        else
        {
            errorMessage = "Email address is NULL";
        }

        Row.IsValidEmail = isValid;
        Row.ErrorDescription = errorMessage;
    }
}
                

In the Script Component Transformation Editor, ensure you have mapped the input email column and configured the output columns IsValidEmail and ErrorDescription.

Best Practices for Scripting in SSIS

• Keep Scripts Focused: Each script should perform a single, well-defined task.
• Use Error Handling: Implement robust error handling within your scripts.
• Leverage SSIS Variables: Use SSIS variables to pass data into and out of scripts, and to control logic.
• Write Readable Code: Use meaningful variable names and add comments where necessary.
• Test Thoroughly: Test your scripts with various edge cases and data conditions.
• Performance Considerations: Be mindful of performance. Complex logic within a Script Component can impact data flow speed. Profile your scripts if performance is critical.
• Security: Be cautious when embedding sensitive information or credentials within scripts. Consider using SSIS Package Configurations or encrypted connection managers.

Further Learning

Explore the following resources to deepen your understanding:

• Microsoft Docs: Creating a Script Component
• SQLIS.com: SSIS Script Task Tutorial
• Video Tutorials on Advanced SSIS Scripting (link illustrative)