Treeview From Database

Hi all,

I am trying to grab data from the database that this application is connecting to and then show entries in a treeview.

 public void dbcall() 
        { 
            SqlConnection sqlconn = new SqlConnection("user id=USERNAME;" + "password=PASSWORD;server=SERVER;" + "database=DBNAME;" + "connection timeout=30"); 
            SqlCommand select = new SqlCommand("SELECT * from MAIN", sqlconn); 
            sqlconn.Open(); 
            SqlDataReader reader = select.ExecuteReader(); 
            DataSet ds = new DataSet(); 
            DataTable dt = new DataTable("MainTable"); 
            ds.Tables.Add(dt); 
            ds.Load(reader, LoadOption.PreserveChanges, ds.Tables[0]); 
 
            sqlconn.Close(); 
 
            foreach (DataRow dr in dt.Rows) 
            { 
 
                //////////// 
 
 
 
            } 
 
        } 
  

The data that I am getting out of the database looks like this:

ID        Hostname         Username         Software
1         host1                  user1               sw1
2         host1                user1             sw2
3         host1                user1               sw3
4         host1                user1               sw4
5         host5                  user5               sw1
6         host5                user5               sw2
7         host5                user5               sw3
8         host5                user5               sw5
9         host9                  user9               sw1
10       host10               user10            sw1

I need the data to be displayed in the tree as follows, though nothing that I have done so far has been able to do it:

host1>user1>sw1
                      sw2
                      sw3
                      sw4
host5>user5>sw1
                      sw2
                      sw3
                      sw5

Any help with this would be appreciated. Thanks in advance.

Once a encountred the same problem and fortunly I have a code that could be near your request

It's pretty simple: (I assume your data is in a datatable)

TreeNode rootNode = null;
Hashtable idToNode = new Hashtable(users.Rows.Count);

// first walk the list of users and create Treeview Nodes.
// we need 2 loops, as we can encounter a user with a parent
// and the parent isn't processed yet.
for(int i=0;i {
        TreeNode newNode = new TreeNode(users.Rows[i]["UserId"].ToString());
        idToNode.Add(users.Rows[i]["UserId"], newNode);
        if((int)users.Rows[i]["ParentId"]==0)
        {
                // found the root
                rootNode = newNode;
        }
}

// now we're going to build the tree!
for(int i=0;i {
        TreeNode nodeToAdd = (TreeNode)idToNode[users.Rows[i]["UserId"]];
        // find parent
        if((int)users.Rows[i]["ParentId"]!=0)
        {
                TreeNode parentNode = (TreeNode)idToNode[users.Rows[i]["ParentId"]];
                parentNode.Nodes.Add(nodeToAdd);
        }
}

// add the complete node structure to the treeview control
myTreeView.Nodes.Add(rootNode);

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Bechir Bejaoui18y ago
Once a encountred the same problem and fortunly I have a code that could be near your request

It's pretty simple: (I assume your data is in a datatable)

TreeNode rootNode = null;
Hashtable idToNode = new Hashtable(users.Rows.Count);

// first walk the list of users and create Treeview Nodes.
// we need 2 loops, as we can encounter a user with a parent
// and the parent isn't processed yet.
for(int i=0;i {
        TreeNode newNode = new TreeNode(users.Rows[i]["UserId"].ToString());
        idToNode.Add(users.Rows[i]["UserId"], newNode);
        if((int)users.Rows[i]["ParentId"]==0)
        {
                // found the root
                rootNode = newNode;
        }
}

// now we're going to build the tree!
for(int i=0;i {
        TreeNode nodeToAdd = (TreeNode)idToNode[users.Rows[i]["UserId"]];
        // find parent
        if((int)users.Rows[i]["ParentId"]!=0)
        {
                TreeNode parentNode = (TreeNode)idToNode[users.Rows[i]["ParentId"]];
                parentNode.Nodes.Add(nodeToAdd);
        }
}

// add the complete node structure to the treeview control
myTreeView.Nodes.Add(rootNode);
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