How Do We Convert Data Type in SSIS?
In SSIS (SQL Server Integration Services), converting data types is a common requirement when transferring and transforming data between different sources and destinations. The ability to convert data types ensures that the data is compatible and can be properly processed by the intended Target system.
Using Data Conversion Transformation
SSIS provides the Data Conversion transformation, which allows you to explicitly convert the data type of a column. This transformation is particularly useful when the source and destination systems have different data types for the same column.
To use the Data Conversion transformation, follow these steps:
- Create an SSIS package or open an existing one.
- Drag and drop the Data Conversion transformation from the SSIS Toolbox onto your Control Flow or Data Flow pane.
- Connect the appropriate source component to the Data Conversion transformation.
- Configure the Data Conversion transformation by mapping input columns to their desired output data types.
- Connect the Data Conversion transformation to the destination component.
- Execute or schedule your SSIS package to perform the data conversion.
Data Conversion Example
Let’s consider an example where we have a source table with a column of type VARCHAR(50) containing numeric values, but we want to load this data into a destination table with a column of type INT. We can achieve this using the Data Conversion transformation.
First, configure a connection manager for both your source and destination databases. Then, create a new SSIS package and add a Data Flow Task to it.
Within this task, add an OLE DB Source component for your source database and configure it to select the desired source table.
Next, add the Data Conversion transformation to the Data Flow Task. Connect the output of the OLE DB Source component to the input of the Data Conversion transformation.
In the Data Conversion transformation editor, map the source column to a new output column with the desired data type (e.g., from string to integer).
Finally, add an OLE DB Destination component and connect it to the output of the Data Conversion transformation. Configure this destination component to insert data into your destination table.
Implicit Data Type Conversion
In addition to explicit data type conversion using the Data Conversion transformation, SSIS also supports implicit data type conversion. Implicit conversion occurs automatically when SSIS can safely convert one data type to another without loss of precision or data integrity.
For example, if you have a source column of type FLOAT and a destination column of type DECIMAL, SSIS can implicitly convert these types without any additional configuration.
Considerations for Data Type Conversion
While performing data type conversions in SSIS, it’s important to consider a few things:
- Data Loss: Some conversions may result in potential data loss or truncation if the Target data type cannot accommodate all values from the source.
- Error Handling: It’s essential to handle any errors during conversions gracefully. SSIS provides various techniques for error handling, such as redirecting error rows or logging them for further analysis.
- Data Validation: Ensure that your converted data is valid and meets any constraints defined in your destination system.
- Performance Impact: Converting large amounts of data during an SSIS package execution can impact performance. Consider optimizing your conversions and using appropriate data types to minimize this impact.
In conclusion, SSIS provides powerful tools for converting data types, allowing you to seamlessly transfer and transform data between different systems. By using the Data Conversion transformation or leveraging implicit conversions, you can ensure that your data is properly formatted and compatible with the Target system.