enforcing data types in SSIS package

I have a SSIS package that imports data from a开发者_开发问答n excel file. One of the columns has mostly numbers (like 12345) but some also have letters (like 123A5)

When i configure the package i can't change the format and it's always recognized as double (probably it only looks at the first lines) .

How can i enforce my own data type , so that it reads the column as string ?

I've also tried to modify the package in visual studio and add the column in the data conversion step but it's still not working.

Yes, as you suspect the Excel driver is checking the first few rows to determine the data type. You can override the default of 8 rows using the MaxScanRows property:

http://support.microsoft.com/kb/236605

http://support.microsoft.com/kb/257819

Alternatively, save the Excel file as .csv first. It's much easier to specify data types for text files.