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Question about how to add rows to sqlite database in app without altering unique changes from each user's interaction with their copy of the database

I am working on an app that would have a database of information. The functionality would be the user would look up entries and could save it to a personal list.
My thinking for how this would work would be that the SQLite database would have two tables, one for the information and one for the personal list.
When the user presses the button to save the info to their list a method is called that creates a personal list object and copies the info held in each field of the selected data to the identical field in the personal list object.
And so that the user knows it has been saved it appears differently like labeled that they have already been saved to the personal list. To do this that it has been saved to the list there would be a variable to keep track of that. Default like this.
var isSavedToList = false;
And when the method is called to save it to the personal list this variable is changed to true.
My question is: Can I add rows to the SQLite database (after the app has been launched and people are using it) without changing the isSavedToList variables on each users device? Since each person's list is going to be different I don't want them to be reset if I update the database with new entries.

Yes, you can. I presume you mean you're doing some kind of program update that adds new rows to the main table. Add your new rows with "isSavedToLiat" set to false (because they can't possibly be set to true because they are new and the user doesn't know about them")

Remove list values based on series of other values

I have a situation wherein a List object is built off of values pulled from a MSSQL database. However, this particular table is mysteriously getting an errant record or two tossed in. Removing the records cause trouble even though they have no referential links to any other tables, and will still get recreated without any known user actions taken. This causes some trouble as it puts unwanted values on display that add a little bit of confusion. The specific issue is that this is a platform that allows users to run a search for quotes, and the filtering allows for sales rep selection. The select/dropdown field is showing these errant values, and they need to be removed.
Given that deleting the offending table rows does not provide a desirable result, I was thinking that maybe the best course of action was to modify the code where the List object is created and either filter the values out or remove them after the object is populated. I'd like to do this in a clean, scalible fashion by providing some kind of appendable data object where I could just add in a new string value if something else cropped up as opposed to doing something clunky that adds new code to find the value and remove it each time.
My thought was to create a string array, and somehow loop through that to remove bad List values, but I wasn't entirely certain that was the best way to approach this, and I could not for the life of me think of a clean approach for this. I would think that the best way would be to add a filter within the Find arguments, but I don't know how to add in an array or list that way. Otherwise I figured to loop through the values either before or after the sorting of the List and remove any matches that way, but I wasn't sure that was the best choice of actions.
I have attached the current code, and would appreciate any suggestions.
int licenseeID = Helper.GetLicenseeIdByLicenseeShortName(Membership.ApplicationName);
List<User> listUsers;
if (Roles.IsUserInRole("Admin"))
{
//get all users
listUsers = User.Find(x => x.LicenseeID == licenseeID).ToList();
}
else
{
//get only the current user
listUsers = User.Find(x => (x.LicenseeID == licenseeID && x.EmailAddress == Membership.GetUser().Email)).ToList();
}
listUsers.Sort((x, y) => string.Compare(x.FirstName, y.FirstName));
-- EDIT --
I neglected to mention that I did not develop this, I merely inherited its maintenance after the original developer(s) disappeared, and my coworker who was assigned to it left the company. I'm not really really skilled at handling ASP.NET sites. Many object sources are hidden and unavailable for edit, I assume due to them being defined in a DLL somewhere. So, for any of these objects that are sourced from database tables, altering the tables will not help, since I would not be able to get the new data anyway.
However, I did try to do the following to filter out the undersirable data:
List<String> exclude = new List<String>(new String[] { "value1" , "value2" });
listUsers = User.Find(x => x.LicenseeID == licenseeID && !exclude.Contains(x.FirstName)).ToList();
Unfortunately it only resulted in an error being displayed to the page.
-- EDIT #2 --
I got the server setup to accept a new event viewer source so I could write info to the Application log to see what was happening. Looks like this installation of ASP.NET does not accept "Contains" as an action on a List object. An error gets kicked out stating that the method is not available.

I will probably add a bit to the table and flag Errant rows and then skip them when I query the table, something like
&& !ErrantData
Other way, that requires a bit more upkeep but doesn't require db change, would be to keep a text file that gets periodically updated and you read it and remove users from list based on it.
The bigger issue is unknown rows creeping in your database. Changing user credentials and adding creation timestamps may help you narrow down the search scope.

in MongoDB how do I update a list of key/value pairs c#

In MongoDB, accessing from C# driver:
I want to keep a list of keys (ints are fine), that have a current value. (Dictionary<int,int>) works well for the concept)
I need to have multiple (10+) machines setting values in this Document. Multiple threads on each machine.
Using C# and the MongoDB driver I need to:
If the key exists, increment the value for that key.
If it does not exist, I need to Add it, and set the value to 1.
Critically Important:
It can't overwrite values others are writing (I.E. No get doc and call Save() to save it)
It has to handle adding values that don't already exist gracefully.
I might be able to have a query that inserts a new document with all of the keys set to values of 0 - if this would help, but it won't be easy, so that is not a preferred answer.
I've tried using a Dictionary, and can't seem to figure out how to update it without it creating:
null,
{ v=1}
On my insert (which doesn't include the k=, and has the null, that I don't want. and causes deserialization to blow)
I don't care what method of serialization is used for the dictionary, and am open to any other method of storage.
Any ideas?
My best guess so far is to keep a list of keys that is separate from the values (two List and append the key to the key list if it isn't found, requery the list and use the first one as the index in the 2nd list. (This seems like it might have concurrency issues that could be hard to track down.)
I would prefer the Linq syntax, but am open to using the .Set (string,value) syntax if that makes things work.

Get Identity Attribute value before inserting in Database

I have a table and it has one of the attribute set as identity. I want to get the value of the identity attribute that would be generated after I enter a value to the database.
I have EmpTable made of EmpID and EmpName. EmpID is set as Identity. I want to fetch the EmpID value before inserting a new row to the database.

I would advise against trying to do this with a table that is set up to use an integer column as the primary key. You will run into concurrency problems if you simply fetch the previous ID and increment it. Instead you should use a GUID (uniqueidentifier in SQL) as your primary key.
This will allow you to generate a new GUID in your code that can safely be saved to the database at a later stage.
http://msdn.microsoft.com/en-us/library/system.guid.newguid.aspx
http://msdn.microsoft.com/en-us/library/ms187942.aspx

Sure the server knows where the auto-increment count is in its sequence, but there is almost nothing useful you can do with that information. Imagine you go to the Post Office and they hand out numbered tickets so they can serve customers in order. Of course you could ask them what the next number they'll give out is, but since anyone can walk in at any time you don't know you'll get that number. If you don't know that you'll get it, you can't do anything with it - e.g. writing it as a reference number on a form would be a mistake.
Depending on what you're trying to do, your two main options are:
Use a client-generated guid as your identifier. This kind of messes up the order so the analogy isn't great, but imagine if each customer who walked in could generate a random number that they are sure would never have been used before. They could use that to fill out forms before taking a number.
Take a number, but do it in a transaction with the other operations. A customer can take a number and use it to fill out some paperwork. If they realize they left their money at home, they just throw everything away and you never call their number.
Why do you think you need this information? Can you use either of these strategies instead?

How to deal with deprecated values in (country-)code lists

Let's say we have a code list of all the countries including their country codes. The country code is primary key of the Countries table and it is used as a foreign key in many places in the database. In my application the countries are usually displayed as dropdowns on multiple forms.
Some of the countries, that used to exists in the past, don't exist any more, for example Serbia and Montenegro, which had the country code of SCG.
I have two objectives:
don't allow the user to use these old values (so these values should not be visible in dropdowns when inserting data)
the user should still be able to (readonly) open old stuff and in this case the deprecated values should be visible in dropdowns.
I see two options:
Rename deprecated values, for instance from 'CountryName' to '!!!!!CountryName'. This approach is the easiest to implement, but with obvious drawbacks.
Add IsActive column to Countries table and set it to false for all deprecated values and true for all other. On all the forms where the user can insert data, display only values which are active. On the readonly forms we can display all values (including deprecated ones) so the user will be able to display old data. But on some of my forms the user should be able to also edit data, which means that the deprecated values should be hidden from him. That means, that each dropbox should have some initialization logic like this: if the data displayed is readonly, then include deprecated values in dropbox and if the data is for edit also, then exclude them. But this is a lot of work and error prone too.
And other ideas?

I deal with this scenario a lot, and use the 'Active' flag to solve the problem, much as you described. When I populate a drop-down list with values, I only load 'active' data and include upto 1 deprecated value, but only if it is being used. (i.e. if I am looking at a person record, and that person has a deprecated country, then that country would be included in the Drop-downlist along with the active countries. I do this in read-only AND in edit modes, because in my cases, if a person record (for example) has a deprecated country listed, they can continue to use it, but once they change it to a non-deprecated country, and then save it, they can never switch back (your use case may vary).
So the key differences is, even in read-only mode I don't add all the deprecated countries to the DDL, just the deprecated country that applies to the record I am looking at, and even then, it is only if that record was already in use.
Here is an example of the logic I use when loading the drop down list:
protected void LoadSourceDropdownList(bool AddingNewRecord, int ExistingCode)
{
using (Entities db = new Entities())
{
if (AddingNewRecord) // when we are adding a new record, only show 'active' items in the drop-downlist.
ddlSource.DataSource = (from q in db.zLeadSources where (q.Active == true) select q);
else // for existing records, show all active items AND the current value.
ddlSource.DataSource = (from q in db.zLeadSources where ((q.Active == true) || (q.Code == ExistingCode)) select q);
ddlSource.DataValueField = "Code";
ddlSource.DataTextField = "Description";
ddlSource.DataBind();
ddlSource.Items.Insert(0, "--Select--");
ddlSource.Items[0].Value = "0";
}
}

If you are displaying the record as read-only, why bother loading the standing data at all?
Here's what I would do:
the record will contain the country code in any case, I would also propose returning the country description (which admittedly makes things less efficient), but when the user loads "old stuff", the business service recognises that this record will be read only, and you don't bother loading the country list (which would make things more efficient).
in my presentation service I will then generally do a check to see whether the list of countries is null. If not (r/w) load the data into the list box, if so (r/o) populate the list box from the data in the record - a single entry in the list equals read-only.

You can filter with CollectionViewSource or you could just create a Public Enumerable that filters the full list using LINQ.
CollectionViewSource Class
LINQ The FieldDef.DispSearch is the active condition. IEnumerable is a little better performance than List.
public IEnumerable<FieldDefApplied> FieldDefsAppliedSearch
{
get
{
return fieldDefsApplied.Where(df => df.FieldDef.DispSearch).OrderBy(df => df.FieldDef.DispName);
}
}

Why would you still want to display (for instance) customer-addresses with their OLD country-code?
If I understand correctly, you currently still have 'address'-records that still point to 'Serbia and Montenegro'. I think if you solve that problem, your current question would be none-existent.
The term "country" is perhaps a little misleading: not all the "countries" in ISO 3166 are actually independent. Rather, many of them are geographically separate territories that are legally portions or dependencies of other countries.
Also note that 'withdrawn country-codes' are reserved for 5 years, meaning that after 5 years they may be reused. So moving away from using the country-code itself as primary key would make sense to me, especially if for historical reasons you would need to back-track previous country-codes.
So why not make the 'withdrawn' field/table that points to the new country-id's. You can still check (in sql for instance, since you were already using a table) if this field is empty or not to get a true/false check if you need it.
The way I see it: "Country" codes may change, country's may merge and country's may divide.
If country's change or merge, you can update your address-records with a simple query.
If country's divide, you need a way to determine what address is part of what country.
You could use some automated system do do this (and write lengthly books about it).
OR
(when it is a forum like site), you could ask the users that still have a withdrawn country that points to multiple alternatives in their account to update their country-entry at login, where they can only choose from the list of new country's that are specified in the withdrawn field.
Think of this simplified country-table setup:
id cc cn withdrawn
1 DE Germany
2 CS Serbia and Montenegro 6,7
3 RH Southern Rhodesia 5
4 NL The Netherlands
5 ZW Zimbabwe
6 RS Serbia
7 ME Montenegro
In this example, address-records with country-id 3, get updated with a query to country-id 5, no user interaction (or other solution) needed.
But address-records that specify country-id 2 will be asked to select country-id 6 or 7 (of course in the text presented to the user you use the country-name) or are selected to perform your custom automated update routine on.
Also note: 'withdrawn' is a repeating group and as such you could/should make it into a separate table.
Implementing this idea (without downtime) in your scenario:
sql statement to build a new country-table with numerical id's as primary key.
sql statement to update address-records with new field 'country-id' and fill this field with the country-id from the new country-table that corresponds with country-code specified in that record's address-field.
(sql statement to) create the withdrawn table and populate the correct data with in it.
then rewrite your the sql statements that supply your forms with data
add the check and 'ask user to update country'-routine
let new forms go live
wait/see for unintended bugs
delete old country-table and (now unused) country-code column from the "address"-table
I am very curious what other experts think about this idea!!