How to add multiple rows one cell in listview from database in C#?

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I have problem with adding values in listview from dadabase, have relation with couple tables and here is OK.
In my case i have table with X rows with same values

PrID|koID
1   |5
1   |8
20  |3
6   |80
13  |3
6   |41

ex. for PrID=1 i should get rows for koID 5 and 8 in one cell
but when add i get this, rows from KoID 5 is in one row in listView, koId 8 in other

column1|column2|column3
1      |A      |Item1
1      |B      |Item1
1      |...    |Item1
2      |C      |Item2
3      |B      |Item3
3      |E      |Item3
3      |...    |Item3

should be like this

column1|column2|column3
1      |AB...  |Item1
2      |C      |Item2
3      |BE...  |Item3

What I have tried:

C#

foreach (DataRow row in dt.Rows)
{
string str = row["kon"].ToString()+" "+row["kov"].ToString();

ListViewItem list = new ListViewItem(row["Id"].ToString());
               list.SubItems.Add(str);
               list.SubItems.Add(row["item"].ToString());
               listView1.Items.Add(list);
}

Posted 16-Mar-20 1:26am

Member 11920272

Updated 16-Mar-20 2:56am

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Maciej Los · Answer 1 · 2020-03-16T02:56:00

You need to group data by PrID. There's few ways to achieve that. One of the simplest is to use Dictionary object.

Take a look at below example:

C#

//sample data 
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[]{new DataColumn("PrID", typeof(int)), new DataColumn("koID", typeof(int))});
dt.Rows.Add(new object[]{1, 5});
dt.Rows.Add(new object[]{1, 8});
dt.Rows.Add(new object[]{20, 3});
dt.Rows.Add(new object[]{6, 80});
dt.Rows.Add(new object[]{13, 3});
dt.Rows.Add(new object[]{6, 41});

//create dictionary object
Dictionary<int, List<int>> d = new Dictionary<int, List<int>>();
//loop through the collection of datatable's rows
foreach(DataRow dr in dt.Rows)
{
	//if key does NOT exist
	if(!d.ContainsKey(dr.Field<int>("PrID")))
		d.Add(dr.Field<int>("PrID"), new List<int>(){dr.Field<int>("koID")});
	else
		d[dr.Field<int>("PrID")].Add(dr.Field<int>("koID"));
}
//add listviewitem and its subitems based on dictionary object
foreach(int k in d.Keys)
{
	ListViewItem lvi = new ListViewItem(k.ToString());
	foreach(int v in d[k])
		lvi.SubItems.Add(v.ToString());
	ListView1.Items.Add(lvi);
}