Converting data types

I've inherited a monster database that needs updating. It has a field called Birthdays that has been a text field and I want to convert it to datetime. The data entry people have been sloppy from time to time and some of the values generate errors when you try and change datatypes. Is there a way to change the datatype and have the oddball values left blank without bombing out the conversion process?

Thanksheh. how big is the database?

if it's not that big, then you can simply store them in a temp table, and move the values over one by one in a cursor style fashion. If it's absolutely enormous, I'd actually create another table just to store the data, and the same cursor fasion. Just make sure you put them in transactions so you can rollback accordingly based on any errors generated.

Since it's a one shot deal, you can even do it out of the database, and just manipulate all the values via code, then do the alter so it doesn't cause any problems.

Do you know specifically what the bad dates are? If so, via code, you can convert the dates based on how the errors were inputted, and update those records. :-\