It's a big big bug:) I tried to solve this problem since I remember because i thought it was on my side but now i have discovered the problem.
Make databse in some manager with table with column that can hold integer but without 'not null' constraint! Simple integer column with allowed null values.
Then make dataset with wizard in visual C# express edition for example.
And now is the thing:
when you use dataadapter.Fill method (generated by wizard not written by me) to populate data into dataset.datatable then:
1.if you have column with all values different from null all is ok,
2.if FIRST row has null value in that column and the rest is whatever-you-want , all is correct
3. but if you have in the FIRST row in that column an integer value then: if Fill populating method meet null value in some further row it raises error:
field cannot hold "<>" value in this column, it expects an Int64. !!!!!!!!!!!!!!!!!
I did it then after compiling application, and the only thing i did was to change values in the table in some databasemanager and then run my app. If i have values in column in order i wrote i had error or hadn't, it depeneds on the first row value, if it has a null or not.
Wiaz