Not having used sql_variant before...

I was under the impression that sql_variant stores different datatypes in the same column. That you can determine which datatype to use for a specific record when you stored the value. So you could have datatypes bit, money, and datetime all in the same column.

Therefore, if you knew what records to pull and made sure to pull only the records where the value in that column was money, you could use the SUM() function.

Am I misunderstanding what sql_variant is and/or how it can be used?