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LINQ: Get all the values from a column in a DataTable in C#

bbirajdar

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13 Oct 2011CPOL

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LINQ: Get all the values from a column in a DataTable in C#

You can get the values from a named column in the DataTable using a single line of code in LINQ.

Steps:

Convert the DataTable object to Enumerable().
Apply the select clause with the column name as field name.

Cast it to a string array.

C#

string[] strSummCities = dtTemp1.AsEnumerable().Select(s => s.Field<string>("City")).ToArray<string>();

License

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

Written By

bbirajdar

Web Developer

India

Software developer by profession, working for a service and product based organisation in India.

Career graph:
Software Programmer since 2002.
Web Developer in ASP.NET since 2004.

Interests:
I love reading the blogs and articles of technology experts. I love codeproject and stackoverflow .

I love to share knowledge and help the programmers. I appreciate if some body corrects my code or my concepts which helps me learn.

Comments and Discussions

any thoughts on distinct?

Member 435337117-Nov-14 18:01

17-Nov-14 18:01

This is great, just wondering if there was a concise way of making it select distinct values?

cheers

Matt

Getting "Specified cast is not valid" error

Silas Pereira5-Dec-12 23:27

5-Dec-12 23:27

Hi,

Thank you for your post, it will be very helpful, if I manage to put this working.
Smile | :)

Smile | :)

I am using it to verify the unique values from a datatable column like this:

C#

Validations.IsUnique<Int16>(data.Tables[0].AsEnumerable().Select(s => s.Field<Int16>(_rotationColumn)))

C#

internal static bool IsUnique<T>(IEnumerable<T> values)
{
    var set = new HashSet<T>();

    foreach (T item in values)
    {
        if (!set.Add(item))
            return false;
    }
    return true;
}

But I am getting a "Specified cast is not valid" in the foreach loop. My database field is tinyint and I thought that casting the T as Int16 would solve the issue (I already tried with string, Int32 and int), but it is not working.

Could you please help me with that?

Thanks.

Silas Pereira

Re: Getting "Specified cast is not valid" error

bbirajdar5-Dec-12 23:42

5-Dec-12 23:42

Cast it as 'byte' . It will work.. See the complete list here http://msdn.microsoft.com/en-us/library/system.data.sqldbtype.aspx[^]

Reason for my vote of 1 Personally attacked because of provi...

Kabwla.Phone20-Oct-11 2:03

20-Oct-11 2:03

Reason for my vote of 1
Personally attacked because of providing alternative.

Matt U.14-Oct-11 2:12

14-Oct-11 2:12

Nice tip. I could have definitely used this in the past, hehe. I will keep it in mind. Thanks Smile | :)

Smile | :)

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