LINQ to get list of data before some given value condition


Anyone please can suggest if in Linq I can select records .I am trying  to get  some data as list.
So for example in the attached worksheet if i can get list of data before NULL value yellow cell  of ColumnA.  Please assume this as a DataTable with columns.

Just need an idea of a linq query and c sharp.

Abhilash Nagar.NET DeveloperAsked:
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Bill PrewIT / Software Engineering ConsultantCommented:
Is there some sort of ID column on the tables as well?  And what order do you want to retrieve the rows, certainly not random?

If there is an ID then I might approach it this way.  First, do a query to find the first NULL value in that column, sorting by ID or whatever other sort order you want to use.

Then do a second query (might be able to merge into one LINQ, but might be easier to understand as two) that returns all rows with an ID less than the one where the first NULL was found, and .ToList() that result set.

Fernando SotoRetiredCommented:
Hi Abhilash Nagar;
The Following query will return a List of DataRow types.
var results1 = (from rec in dt.AsEnumerable().TakeWhile(d => d.Field<String>("ColumnA") != null )
                select rec).ToList();

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This query will return a List of Anonymous type.
var results2 = (from rec in dt.AsEnumerable().TakeWhile(d => d.Field<String>("ColumnA") != null)
                select new
                    ColumnA = rec.Field<String>("ColumnA"),
                    ColumnB = rec.Field<int>("ColumnB")

Open in new window

Abhilash Nagar.NET DeveloperAuthor Commented:
Thank you , I will try this one and will let you know the output.

Thanks again for your time.
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Fernando SotoRetiredCommented:
OK, if you have a question just ask.
Abhilash Nagar.NET DeveloperAuthor Commented:
Thanks for the response, it really helpful. One quick question again can we get result by index range for example from rowindex 0 -115 ,can we get those records using LINQ.

Fernando SotoRetiredCommented:
Hi Abhilash;

The List object has a count method and seeming the collection of the records starts a the first til it reaches the null value your index would be 0 - (Count - 1).

Abhilash Nagar.NET DeveloperAuthor Commented:
Thanks everyone yes got the solution.Thanks.

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Fernando SotoRetiredCommented:
Not a problem Abhilash, glad to help.
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