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How to get data from linq query using select

I'm testing a simple LINQ select query and want to get two DateTime values from the table, but I'm doing something wrong here and need to know what I'm doing/thinking wrong?
My query:
var test = from x in db.Projects where x.ID == 1 select x;
Then I try to get on of the values like this:
DateTime Date = test. ?????
Here I thought I should get a suggestion from the Intellisense after the dot to pick the value from the column StartDate the table, but this isn't working.

If you need multiple matches...
Are you sure that you have multiple Project objects that have the same ID of 1 which your query currently suggests? If that is the case, then your query should return all of the records that meet that constraint via the Where() method :
// Get your Projects that meet your criteria
var test = db.Projects.Where(p => p.ID == 1);
If you need to access properties from these elements, you could either loop through them explicitly :
// Iterate through each match that was found
foreach(var t in test)
{
// Access your properties here
DateTime dt = t.YourDateProperty;
}
Or you could accomplish this using a Select() statement to only pull the properties that you need :
// This will return a collection of Dates mapped from each element in your collection
var testDates = db.Projects.Where(p => p.ID == 1)
.Select(x => x.YourDateProperty);
If you only need a single match...
If you only need to match a single element within your collection, you might consider using the First(), Single() or their equivalent FirstOrDefault() and SingleOrDefault() methods, which will return a single entity that you can use as expected :
// This will return the first Project with an ID of 1
var test = db.Project.FirstOrDefault(p => p.ID == 1);
// If it was successful
if(test != null)
{
// Then you can safely access it here
DateTime dt = test.YourDateProperty;
}
The only difference between the methods mentioned (normal vs OrDefault()) is that the OrDefault() methods will return null if no matching elements are found, so they generally require a null check as seen above.

test is going to be an enumeration (IEnumerable<>, IQueryable<>, etc... many are applicable) of your Project type. So if, for example, you want the first record, you might do this:
DateTime Date = test.First().SomeDateProperty;
All of the data returned from your query is in test. It could be zero records, one record, many records, etc.

In test you will have a collection which matches the condition x.ID == 1. You should iterate through that collection and take your needed properties.
Edit
I suggest you to use the syntax:
var result = db.Projects.FirstOrDefault(x => x.ID ==1);

this is such as:
var date = test.FirstOrDefault();
DateTime? Date = date != null ? date.StartDate : null;

Dynamic Linq - Joining a table with 1 to many relationship

I'm using Dynamic Linq as the backend to an in-app reporting tool and I've hit a problem that I can't get round where I have to access a table that has a 1:M relationship .
My simplified data structure is this:
If I were querying this in standard Linq I'd write the query as:
from a in context.Table_A
select new
{
a.RefNo,
val = from b in a.Table_B
where (b.A_ID == a.ID)
where (b.code == "A0001"
select(b.Value).FirstOrDefault()
}
This works without any problem. However, when I try the query using Dynamic Linq I can't get the join to work.
From the code below you can see what I'm getting at but obviously I can't use the "a." and the "a.Table_B" references in the query. What do I have to do to be able to access Table_B in this context?
string select = "new (Ref_No,
val = from b in a.Table_B
where (b.A_ID == a.ID)
where (b.code == \"A0001\"
select(b.Value).FirstOrDefault()";
var results = context.Table_A.Select(select);
Edit 1:
To answer #Hogan's comment - Why don't I use join: The reports system is dynamic and the select statement may or may not be joining on to Table_B (or indeed joining on to Table_B multiple times) so the join has to be optional. My other issue with this is that unlike the Select method where I can pass in a string as a parameter (allowing me to make it dynamic quite easily) the Join() method can't be called in that way. The closest thing I've found is a dynamic Linq join extention method, something I may have to consider using but I've a feeling that this will be cumbersome with the dynamic select().
Edit 2:
Based on Hogan's suggestions I've got this far:
delegate string searchTableA(Table_A a);
public void Search()
{
....
searchTableA sel = (a) =>
{
return (from b in context.Table_B
where (b.A_ID == a.ID)
select (b.Value)).FirstOrDefault();
};
var res = context.Table_A.Select(sel);
}
This gives the error: 'System.Data.Entity.DbSet<TestDynamicLinqJoins.Table_A>' does not contain a definition for 'Select' and the best extension method overload 'System.Linq.Dynamic.DynamicQueryable.Select(System.Linq.IQueryable, string, params object[])' has some invalid arguments

Hard to give exact code because I don't know the types of your elements, but something like this would work fine using delegates.
delegate string searchTableA(elementType a);
searchTableA sel = (a) =>
{
return from b in a.Table_B
where (b.A_ID == a.ID)
where (b.code == "A0001")
select(b.Value).FirstOrDefault();
};
var results = context.Table_A.Select(sel);

Linq Extension method for Join

I am in the process of learning LINQ, ASP.NET, EF, and MVC via online video tutorials. I would love some help understanding Joins in LINQ extension method syntax.
For simplification, I have two tables (these map to a SQL DB):
User Table:
public int userID{get;set;}
public string firstName{get;set;}
...
Address
public int ownerID{get;set;}
public int value{get;set;}
public string Nickname{get;set;}
public string street{get;set;}
public string zip{get;set;}
...
Let's say I want to find all the property that a particular user owns. I believe I can do something like this:
var test = db.User
.Join(db.Address, user => user.userID, add => add.ownerID, (user, add) => new { user, add });
Source: http://byatool.com/c/linq-join-method-and-how-to-use-it/
This should be equivalent to
SELECT * FROM User a JOIN Address b on a.userID = b.ownerID
Please confirm that this is correct.
Now, what if I wanted to find all property that a particular user owns that has a value greater than x. Let's take it a step further and say x is a result from another LINQ query. How do I force execution of x inside of a second query? Do I even have to consider this, or will LINQ know what to do in this case?
Thanks
EDIT:
When I try to use the result of a query as a parameter in another, I am required to use a greedy operator to force execution. Many people like to use .Count() or .ToList(). I only expect x (from example above) to return 1 string by using .Take(1). If I append ToList() to the end of my first query, I am required to use x[0] in my second query. This seems like a messy way to do things. Is there a better way to force execution of a query when you know you will only have 1 result?

If I understand your question, you're trying to do a conditional on a joined model?
var query = db.Users.Where(x => x.Addresses.Where(y => y.Value >= yourValue).Any());
That will return all users who have a property value greater than yourValue. If you need to return the addresses with the query, you can just add Include to your query. For example:
query.Include(x => x.Addresses);
You don't need to manually do that Join that you have in your example.

Selecting several objects based on array of IDs

I have an array of ProgramIDs and would like to create a number of Select statements dynamically depending on how many ProgramIds there are.
For example:
var surveyProgramVar = surveyProgramRepository.Find().Where(x => x.ProgramId == resultsviewmodel.ProgramIds.FirstOrDefault());
This is an example of the select statement working with a single ProgramId.FirstOrDefault(). How do I create a list/array of SurveyProgramVars and select for each ProgramIds in the array?

It won't be necessarily optimal, but you might try:
var surveyProgramVar = surveyProgramRepository.Find()
.Where(x => resultsviewmodel.ProgramIds.Contains(x.ProgramId));

You could try something like:
var surveyProgramVar = surveyProgramRepository.Find().Where(x => resultsviewmodel.ProgramIds.Contains(x.ProgramId));
Tip: If the Find() method does a hit on a database, would be nice if you create a specific method to to a IN statment on the query. If you does not do this, it will take all records on a table and filter it in memory (linq to objects), which works but not very nice. Your code could be something like:
var surveyProgramVar = surveyProgramRepository.FindByProgramsId(resultsviewmodel.ProgramIds);

How Would I Write This In LINQ2SQL?

I am slowly porting over an app from MySQL to use Linq2Sql - but one query has stumped me a bit.
SELECT * FROM Pages WHERE DomainID = #reportid AND (PageContent REGEXP 'display:[ \t]*none') > 0 ORDER BY URL ASC
Any ideas on how I would write something like this with Linq2SQL? Its the REGEXP bit thats got me stumped?

There is no way built in to LINQ to SQL, but you have a couple of other choices. The first is to load your strings in as in-memory objects which you can apply Regex functions to. I'm not a big fan of this since it looks like you're potentially getting some very big strings to match against.
The second option is to leverage SQL CLR as described here. This effectively lets you create a stored procedure that gets linked to a CLR method that you create. Whenever you call the method in a LINQ to SQL context, it gets converted to a stored procedure call. Then you use a query like this:
var q = from p in context.Pages
where p.DomainId == reportId &&
RegExMatch(p.PageContent, "display\:[ \t]*none")
select p;

Why not use LINQ to return items that match on reportid and that contain 'display:', to minimise the amount of data being returned from the server, and then use regex on client side to filter that list down?
var query = Pages.Where( p => p.DomainId == 1 && p.PageContent.IndexOf("display:") > 0).OrderBy( o => o.URL );
var regex = new Regex(#"display\:[\t]*none");
foreach (var page in query)
{
if( regex.IsMatch(page.PageContent) )
{
// Do whatever...
}
}