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migrating an access multi valued field column to c#

I am attempting to use the Microsoft.ACE.OLEDB.12.0 driver to read data from an access database. came upon an odd situation. one of the columns in the access database shows as a comma delimited list of ids.
Wells
________
345,456,7
6,387
when I looked at the column definition in access I thought it would say string but it does not, it says number. so I guess it is storing an array of integers in a single column?
I'm having a tough time getting a data reader to pick this up.
using
var w = DB_Reader.GetValue(DB_Reader.GetOrdinal("Wells"));
results in the error
The provider could not determine the Object value. For example, the
row was just created, the default for the Object column was not
available, and the consumer had not yet set a new Object value.

Well, at the end of the day, you can think of the mutli-value column as in fact a child table.
So, if you looking to migrate a master and child table, then in YOUR database, you need a relational set of tables to re-create what Access is doing behind the scene.
So, lets take a multi-value example and query.
Say we have this sql query in Access:
SELECT ID, Person_Name, FavorateColors FROM tPerson;
But, "favorite colors" is one of those MV columns. (and I should point out with the HUGE movement towards no-sql databases - they also often work this way also - same for XML or JSON data for that matter. However, be it some XML, JSON or Access mutli-value features? Well, you need that child table if you going to adopt a relational data model to represent this data.
Ok, so we run the above query, and you get this output:
In fact, when I used the lookup wizard - I picked a child table called tblColors.
but, how can we explode the above query to dig out the data?
Change the above query to this:
SELECT ID, Person_Name, FavorateColors.Value FROM tPerson
Note how we added ".value" after the MV column name. Now, when you run the query, you get the SAME result as if you had two tables, and did a left join. The parent table rows will like any relational database simple repeat for each child table value, and you get this:
Note how now the PK value and the row is repeating for each child mv value.
So, you are quite much free to query as per above - you get what amounts to a left joined table, and of course the parent record repeats.
So, just like XML, JSON, or in fact a query or a table of data with repeating parent row, and child rows? Well, you quite much forced to write code to split out this data, or re-normalize the data. This of course is far more common when receiving say JSON/XML data, or in fact often say data from a Excel sheet.
So, you have to process out the child record data, and create a relation for that data.
And thus now our question becomes how can we import JSON/XML/Excel data that really should have used two relational database tables.
So, assuming we want to process this data? You process it the same as for any data you have that should have been two related tables in the first place.
it really depends if this is a one time import, or you have to do this all the time?
If it was a one time deal, then I would use Access, and use a make table query based on the above query. You would in fact have to pluck up the PK ID from the child table. In above there is a child table called colors - we just missing that "junction" table in between that Access automatic created. The hidden tables are not exposed, and thus I would simply use a make table query in access, and then add a FK column that is the PK value from the tblColors.

Winforms with SQL Server : Define relations in SQL

When I write C# applications, I use to write sql relations as inner join for example, in the query:
select xxx from TableA as A inner join TableB...
I don't really see why I should define these realtions (hard defined) in Management Studio.
Should I, and why if required?
Regards

Two main reasons and a minor third one: data-integrity and performance - and documentation.
Performance is simple: if you define a relationship between two tables you will normally automatically create an index on those two columns, and your database will use those indexes to speed up look-ups when they can be used.
As for data-integrity, even though you leave the important part of your join out of your example, you assume in a join that a foreign key field can only contain values that exist in the primary key field. Your database can make sure of that, and will make sure of that when you define those relations in SQL server.
If you do not define those relationships, you could easily create a situation where you have, say, Orders, that belong to Customer 12345, who does not exist in your Customer table.
Or you could delete Customer 23456, leaving all their Orders in your system, but without an existing Customer.
A final reason is documentation: your database is not only made to be accessed by your code. If someone else accesses your database and sees only unconnected unrelated tables, how will they know that field cstID in table CstOrderHdr happens to be a reference to field id in table Relations where Relation.RelTyp = 'Customer'? Who is to stop them from filling in 0, null or a random number?

LINQ to SQL: Invalid column name 'DepartureGate', even though the column exists

I absolutely do not get this. The column exists in the table, I've ensured that the application is executing the query against the proper table in the proper database, and it still reports that it's an invalid column name.
I'm running NET 4.0, SQL Server 2008 Express Edition. Does anyone have any similar experience?
Executing queries against any other column name in the same table in the same database works extremely excellently. I added this column today and for some reason my application refuses to acknowledge the existence of this column.
Relevant column definition:
Relevant code:
(from x in flightDataContext.FlightDatas
where x.FlightDataId == FlightDataID && x.Departure == true
select new
{
x.ArrivalStationCode,
x.ArrivalStationName,
x.DepartureTime,
x.DepartureGate
}).SingleOrDefault();

I also faced the same problem.You can try the following solutions.
You should update your classes after the database changed(drag and drop your tables to the linq to sql file), so that the column is accessible with object name. if still problem exists then
the value you are saving in the coloumn is greater then the size specified for the coloumn. try varchar(MAX) if your coloumn is of varchar type.

When I encountered this error, I discovered that I had some spurious [Key] attributes on one of my Model objects that wasn't actually part of the unique key definition for that object's table. They had been innocuously sitting there until I refactored another of the object's relationships. Once I removed them, the error about the columns being invalid vanished.

Try this. Before this , delete the table and drag drog the table again on the DBML file and save the DBML.
var flight= flightDataContext.FlightDatas.SingleOrDefault(x=>x.FlightDataId == FlightDataID && x.Departure);
Now you can access:
flight.ArrivalStationCode,
flight.ArrivalStationName,
flight.DepartureTime,
flight.DepartureGate

Retrieving scalar data using .xsd dataset object?

Can someone suggest the best way to retrieve a scalar value when the site uses .xsd files for the data sets? I have such site where before I commit to a insert task I need to verify duplicates.
Back in the day one would just instantiate a new connection and command object and run the query through BLL/DAL - easy job. With this prepackaged xsd file that the Studio creates for you I have no idea how to do it.
Thanks,
Risho

First, i would recommend to add an unique index in your database to ensure that it's impossible to create duplicates.
To answer your question: you can add queries to the automatically created TableAdapters:
How to: Create TableAdapter queries
From MSDN
TableAdapter with multiple queries
Unlike standard data adapters, TableAdapters can contain multiple
queries to fill their associated data tables. You can define as many
queries for a TableAdapter as your application requires, as long as
each query returns data that conforms to the same schema as its
associated data table. This enables loading of data that satisfies
differing criteria. For example, if your application contains a table
of customers, you can create a query that fills the table with every
customer whose name begins with a certain letter, and another query
that fills the table with all customers located in the same state. To
fill a Customers table with customers in a given state you can create
a FillByState query that takes a parameter for the state value: SELECT
* FROM Customers WHERE State = #State. You execute the query by calling the FillByState method and passing in the parameter value like
this: CustomerTableAdapter.FillByState("WA").
In addition to queries that return data of the same schema as the
TableAdapter's data table, you can add queries that return scalar
*(single) values.* For example, creating a query that returns a count of
customers (SELECT Count(*) From Customers) is valid for a
CustomersTableAdapter even though the data returned does not conform
to the table's schema.

how to specify multiple restiction values in connection.Getschema in c sharp

i used
odbcConnection.Getschema("Columns",new string[]{null,null,"Table1"})
to get the column names of a Table 'Table1'
now how do i specify multiple tables in the restriction in this function call to get list for multiple tables?
and also is there any way to say to get the info for all tables except Table1(not operator)

You could not get the table schema for multiple special tables. You could call
odbcConnection.GetSchema("Columns",new string[]{"catalog1", "owner1"})
to get all tables' schema in catalog1.owner1. And then, you need to find what you want manually.