Fetch Data From DataTable

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I want to Retrieve only First two characetrs from DataTable's Column Which are Unique in C#

I Can Take Out Unique Records So Currently I Need only Two Characters

e.g.
My DataTable is

C#

SrNo  VrNo
 1    BR123
 2    BP321
 3    BR111

So I Want Result as

C#

VrNo
BR
BP
BR

And After That I Can take out Unique

Please Help Me How Can I Do This...?

Posted 30-Jul-14 23:39pm

prashantttt

Updated 30-Jul-14 23:53pm

Thanks7872

v2

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**Nirav Prabtani** · Answer 1 · 2014-07-30T23:47:00

Solution 1

try with Substring(0,2) this.. :)

C#

string strData=dt.Rows[0]["VrNo"].toString();
string YourOutput=strData.Substring(0,2);

Posted 30-Jul-14 23:47pm

Nirav Prabtani

Comments

prashantttt 31-Jul-14 6:20am

This will increase processing time that's why I'm looking for any other way
like the way in sql server select left()

Nirav Prabtani 31-Jul-14 6:24am

I agree with you but you have tag c# , otherwise i'll suggest you same if you tah it SQL instaed

CHill60 31-Jul-14 6:29am

Answered as per the question and tags! ~~Giving a 4 rather than a 5 because it could have been done in a single line - I can be picky like that :-)~~. Changed my mind - giving it a 5 because splitting the lines highlights the bit that does the substring

Nirav Prabtani 31-Jul-14 6:43am

Thanks .. :)

CHill60 31-Jul-14 6:25am

This is exactly the same as sql server left() ... how are you populating your datatable?

prashantttt 31-Jul-14 6:39am

I've written my datatable in question

CHill60 31-Jul-14 6:50am

I can see what is in it ... how does the data get into the datatable?

prashantttt 31-Jul-14 6:52am

From excel file

Nirav Prabtani 31-Jul-14 6:58am

You got both solution one is mine or second is using sql.
so apply whatever you like why are you still worried???

prashantttt 31-Jul-14 7:01am

How is SQL...?
as I'm reading datatable from excel file..

Nirav Prabtani 31-Jul-14 7:03am

Than why you wrote "This will increase processing time that's why I'm looking for any other way
like the way in sql server select left()" above???
If you dont want to use it by SQL else try my solution and mark it as solved if it helps you.

prashantttt 31-Jul-14 7:08am

I wrote about processing time jzt because u r checking row by row and there can be 10000's of rows in my excel

CHill60 · Answer 2 · 2014-07-31T00:21:00

Further to solution 1, you haven't mentioned how you are taking out the unique records.
If you use a HashSet you can do both the truncation to 2 characters and the "uniqueness" at the same time.
(Nice example here[^] but the adverts are annoying)
Essentially if you try to add a duplicate entry into the Set no exception is raised but the duplicate is not added. It's also quite quick!

For example

C#

HashSet<string> hs = new HashSet<string>();
foreach (DataRow row in dt.Rows)
    hs.Add(row["VrNo"].ToString().Substring(0,2));

Using the HashSet is the same as going through your datatable e.g.

C#

foreach (string s in hs)
    // do something with s

_Amy · Answer 3 · 2014-07-31T01:16:00

Solution 3

Try this:

C#

var res = dt.AsEnumerable().Select(s => s.Field<string>("VrNo")).Distinct().Select(s => s.Substring(0, 2));
    foreach (var r in res)
        Console.WriteLine(r);</string>

--Amy

Posted 31-Jul-14 1:16am

_Amy