Pivot table using LINQ

Question

0.00/5 (No votes)

See more:

Hey everyone. I have such a table:

------------
name | value
------------
n1   | v1
n2   | v2
n3   | v3
------------

What is needed to be done is this:

------------
n1 | n2 | n3
------------
v1 | v2 | v3
------------

The thing is, table is a real life MSSQL table sitting in a database. Currently I am pivoting it using T-SQL Pivot, but need to do it with LINQ. Apart from that, new table have to be sortable as a regular table.
So, is that even possible? If it is - is there anyone, who knows how to do it? BTW, everything is dynamic here, and dynamic sql is used for T-SQL, columns are dynamic, etc.

What I have tried:

I've read probably everything on the net how to pivot tables, but nothing worked so far.

Posted 7-Mar-20 7:12am

csrss

Updated 8-Mar-20 10:52am

Maciej Los

v3

Add a Solution

Comments

Maciej Los 7-Mar-20 14:51pm

There's no data on which data can be pivoted (group by).
:(

2 solutions

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)

Maciej Los · Answer 1 · 2020-03-08T10:53:00

Take a look at below example (created in LinqPad):

C#

void Main()
{
	DataTable srcdt = GetInitialData();
	List<KeyValuePair<string, string>> data = srcdt.AsEnumerable()
		.Select(x=>new KeyValuePair<string, string>(x[0].ToString(), x[1].ToString()))
		.ToList();
	
	DataTable dstdt = new DataTable();
	List<string> cols = data.Select(x=> x.Key).Distinct().ToList();
	dstdt.Columns.AddRange(cols.Select(x=>new DataColumn(x, typeof(string))).ToArray());

	if(cols.Count != srcdt.Rows.Count)
		Console.WriteLine("The number of columns does not equal to no. of rows in source table!");
	else
	{
		DataRow dr = dstdt.NewRow();
		foreach(KeyValuePair<string, string> kvp in data)
		{
			dr[kvp.Key] = kvp.Value;
		}
		dstdt.Rows.Add(dr);
	}
	dstdt.Dump();
}

// Define other methods and classes here
DataTable GetInitialData()
{
	DataTable dt = new DataTable();
	dt.Columns.AddRange(new DataColumn[]
		{
			new DataColumn("name", typeof(string)),
			new DataColumn("value", typeof(string))
		});
	dt.Rows.Add(new object[]{"n1", "v1"});
	dt.Rows.Add(new object[]{"n2", "v2"});
	dt.Rows.Add(new object[]{"n3", "v3"});

	return dt;
}

Note: If there would be non-unique data, you'll be in trouble ;)

Gerry Schmitz · Answer 2 · 2020-03-07T09:25:00

Solution 1

Don't know why you "need" to use LINQ (you could use it for "some" parts).

Create a <name,value> dictionary and "sum" the values by adding to and updating the dictionary.

At "report" time, print the "keys" as headings, and the "values" as column values.

(With LINQ, you groupby on name with a sum on value, then foreach 2 times for printing, assuming its now ordered)

For "report" / printing substitute array, data row, etc. based on context.

Posted 7-Mar-20 9:25am

Gerry Schmitz

Updated 7-Mar-20 9:33am

v2

Comments

csrss 7-Mar-20 15:30pm

There is no numeric data - all rows and columns consist of string values. No, I cannot do it like you say - pivoted table is applied to a bigger query so the result table is returned which has all possibilities of sorting and filtering data data.

[no name] 7-Mar-20 15:35pm

It works for "strings", assuming they're unique. If the strings are NOT unique, then PIVOTING WON'T WORK. The rest of your "reason" makes no sense.

csrss 7-Mar-20 15:39pm

You see, I have already tried such solution as yours, but unfortunately it does not work.