在同一条语句中多次从同一表中选择同一列

Question

I am converting a VB6 app to C# with an SQL Server back end. The app includes a very general query editor that allows the user to write any select query and return the results visually in a grid control. Some of the tables have several hundred columns (poor design, I know but I have no control over this). A typical use case for an admin user would be to

select * from A_Table_With_Many_Columns

However, while they want to be able to view all the data, they are particularly interested in 2 columns and they want these to be displayed as the first 2 columns in the grid (instead of 67th and 99th for example) so instead they execute the following statement:

select First_Interesting_Field, Second_Interesting_Field, * 
from A_Table_With_Many_Columns

Then they will go and modify the data in the grid. However, when saving this data, it results in a concurrency violation ( DBConcurrencyException ). This worked fine with the connected RecordSets of VB6 but not so well in C#. I have tried a myriad of solutions to no avail.

1. Does anyone know how to handle this exception in a generic way? (Remember, the user can type ANY select statement or join etc. into the query editor)

2. Does anyone know how I might manipulate the columns returned such that I delete the 2 columns that appear further on in the list? (My difficulty here is that if the column name in the database is EMail so I do select Email, * from Blah the 2 pertinent columns returned are EMail and ADO.NET or C# aliases the second EMail column from the * portion of the query as EMail1 so I am not able to detect the second column as a duplicate and remove it)

3. Does anyone have an alternate solution I have not thought of?

Thank you very much

Answer 1

Actually, you could rename all variables to something like email_userdefined by doing something like this:

SELECT First_Interesting_Field as First_Interesting_Field_userdefined, Second_Interesting_Field as Second_Interesting_Field_userdefined, * from A_Table_With_Many_Columns

Replace user_defined with whatever you want, like order number or anything else user acceptable