Sean Lange (7/22/2013)
I realize that my example above is not really accurate because once a foreign key is established you can't change the datatype and the datatypes must match when creating the key. I was trying to illustrate the point.Of course if we had ddl to work with this would be a LOT easier.
My guess is that the OP is trying to change the datatype with the designer GUI in SSMS, so that when he saves the table, the attempted modification fails because the datatype of a column that participates in a foreign key relationship can't be changed. The datatype stays the same, so the truncation errors occur when trying to insert longer strings. My SSMS (ver. 11.0.3350.0) pops up a bunch of error warnings when I try to save a table modification like this, though. OP, can you describe how you are changing the datatypes?
Jason Wolfkill