How to multiply column values with all other column values in datatable in c#.net

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how to multiply datatable column with all column for same datatble columns:

my datatable is:

col4 	col3	col2	col1
8	         5	 1	 1
9	         2		
7	         4

expected result:

col4	col3	col2	col1
     8	          5	 1	 1
     8	          2	 1	 1
     8	          4	 1	 1
     9	          5	 1	 1
     9	          2	 1	 1
     9	          4	 1	 1
     7	          5	 1	 1
     7	          2	 1	 1
     7	          4	 1	 1

What I have tried:

C#

for (var v = 0; v < dt.Rows.Count; v++)
{
	int s = 0;
	for (var k = dt.Columns.Count; k > 0; k--)
	{
		DataRow d = dtRecord.NewRow();
		if (dtRecord.Columns.Contains(dt.Columns[k - 1].ToString()))
		{
			d[dt.Columns[k - 1].ToString()] = dt.Rows[v][dt.Columns[k - 1].ToString()].ToString();
			if (s == 0)
				dtRecord.Rows.Add(d);
			else
				dtRecord.Rows[v][dt.Columns[k - 1].ToString()] = dt.Rows[v][dt.Columns[k - 1].ToString()].ToString();
			s++;
		}
	}

}<pre>

Posted 23-Aug-17 2:45am

Member 10371658

Updated 23-Aug-17 4:54am

Graeme_Grant

v2

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Comments

ZurdoDev 23-Aug-17 11:29am

It would probably be easier to do it in sql first. But, why isn't your code working?

Graeme_Grant 23-Aug-17 11:43am

It is unclear how the data is being generated or what type of app it is being used in as no context is given... It could be UI generated rather than db ...

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Graeme_Grant · Answer 1 · 2017-08-23T02:52:00

Solution 1

This should help: DataColumn.Expression Property (System.Data)[^] and this: Creating Expression Columns | Microsoft Docs[^] (code samples included)

UPDATE: If you mean auto-populate, then you need to do that manually - take the data from your original DataTable and generate a new one... Something like this:

C#

DataTable ExpandDataTable(DataTable dt)
{
    var dt = new DataTable();
    // configure columns
    // iterate and build new DataTable
    return dt;
}

Posted 23-Aug-17 2:52am

Graeme_Grant

Updated 23-Aug-17 5:05am

v2

Comments

Member 10371658 23-Aug-17 10:27am

not helpful, as i am expecting.

Graeme_Grant 23-Aug-17 10:53am

~~What are you expecting?~~

Member 10371658 25-Aug-17 12:36pm

i have the following data table:
col4 col3 col2 col1
8 5 1 1
9 2
7 4
expecting result:
col4 col3 col2 col1
8 5 1 1
8 2 1 1
8 4 1 1
9 5 1 1
9 2 1 1
9 4 1 1
7 5 1 1
7 2 1 1
7 4 1 1

Every column multiply with all other column which is make the unique row. see the above tables