In this post I demonstrate the Aggregate and Data Conversion Transformations in SQL Server Integration Services (SSIS). Aggregate functions summarize data – such as averaging or summing. The actual aggregate function available will depend on the data type of field that the transformation is being applied against. For example an average function is not available for data stored in a text data types, but it is for numeric data types. All logical stuff, however data is sometimes stored in an incorrect format and requires a Data Conversion transformation to be applied before an appropriate aggregate transformation can be applied. In this example we calculate an average monthly spend for customer data that is stored in text format.