in here you can have two option,
one way is using nullable type, as below (replace the DATA_TABLE_VALUE from you actual value)
DateTime? value = Convert.IsDBNull([DATA_TABLE_VALUE]) ? null : (DateTime?)[DATA_TABLE_VALUE];
2nd option,
Since DateTime is a value type (like
int
), a Null value cannot be assigned to it. In this instance you can use
DateTime.MinValue
or
DateTime.MaxValue
instead.