Be careful in situations where you have different data types in the same column.

For example, in my spreadsheet, the first four rows contain information that really has nothing to do with the data. The real data starts from the fifth row and down. So in my example, I have integer data in the first column (starting from the fifth row). However, cell A1 contains a title that is a string. If I use cast(f1 as int) in my code, it will fail on cell A1.

In your case, you're casting to a varchar so no big deal, but if you are casting to a numeric data type you'll need to be aware of the pit falls.

Bottom line - lots of error checking and data massaging may be required.