LINQ query to get the single column value from a datatable

Question

0.00/5 (No votes)

See more:

var Q1 = (ds.Tables[1].AsEnumerable()
                .Select(r => r["ATTRITION_RATE"])
                ).ToList();

            var Q1a = (ds.Tables[1].AsEnumerable()
                .Select(r => r["ATTRITION_RATE"])
                );

            var Q1b = (ds.Tables[1].AsEnumerable()
                .Select(r => r["ATTRITION_RATE"])
                ).ToString();

ATTRITION_RATE column has the value 12.45 (data type : double).

Results:
Q1--it is returning a list which holds the value
Q1a --system.data.enumerablerowcollection
Q1b--System.Data.EnumerableRowCollection`1[System.Object]

Here I want to get the direct value from the data table, how to achieve this.

What I have tried:

I am new to LINQ query stuff,
tried this method but no use

var q1 = ds.Tables[1].AsEnumerable().Select(x => x.Field<double>("ATTRITION_RATE"));
           var q2 = ds.Tables[2].AsEnumerable().Select(x => x.Field<double>("ATTRITION_RATE"));
           var q3 = ds.Tables[3].AsEnumerable().Select(x => x.Field<double>("ATTRITION_RATE"));
           var q4 = ds.Tables[4].AsEnumerable().Select(x => x.Field<double>("ATTRITION_RATE"));

Posted 5-Dec-20 5:24am

Virendra S from Bangalore, Karnataka

Updated 5-Dec-20 6:13am

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2020-12-05T06:13:00

OK, the last one is never going to work: unless a class specifically implements a ToString override method the default object is used - which returns the fully qualified name of the type, not anything to do with the content.
So even a simple List will give you nothing useful:

C#

List<int> myList = new List<int> { 1, 2, 3 };
Console.WriteLine(myList.ToString());

Will only give you:

System.Collections.Generic.List`1[System.Int32]

The others return exactly what you asked them to: they went through the entire DataTable, extracted the "ATTRITION_RATE" column values, and put them into an anonymous type collection - in the first case you converted that to a List, in the second you didn't.

If you want a single value from a collection rather than a new collection of items, then don't use Select - use FirstOrDefault[^] if you have a condition, or just get the data directly:

C#

double value = myDataTable.Rows[0].Field<double>("ATTRITION_RATE");