SQL数据的C＃树形视图

Question

I have a SQL table looking like this:

orderID       customerName        orderDate          valueTotal
================================================================
   1             JohnA            01/02/2013            100
   2             AmandaF          01/02/2013            140
   3             JohnA            05/03/2013             58
   4             FredM            05/03/2013            200

And I want to order this information on a treeView by either orderDate or customerName , depending on user settings so that it looks like this if ordered by customerName:

JohnA
    01/02/2013
    05/03/2013
AmandaF
    01/02/2013
FredM
     05/03/2013

Or like this if ordered by orderDate:

01/02/2013
    JohnA
    AmandaF
05/03/2013
    JohnA
    FredM

What would be the best way to achieve this?

EDIT: I'm using windows forms

Answer 1

If you're using ADO.Net, test this:

Dictionary<string, List<string>> groups = new Dictionary<string, List<string>>();

//set these dynamic
string groupingFieldName = "customerName";
string targetFieldName = "orderDate";


SqlDataReader rdr = sqlCmd.ExecuteReader();
while (rdr.Read())
{
    if (!groups.ContainsKey(rdr[groupingFieldName].ToString()))
    {
         groups.Add(rdr[groupingFieldName].ToString(), new List<string>());
    }
    groups[rdr[groupingFieldName].ToString()].Add(rdr[targetFieldName].ToString());
}

//next, iterate the dictionary and populate the treeView
foreach (KeyValuePair<string, List<string>> group in groups)
{
     //add to treeView
}

Please note that this is not tested. You still need to test it.

Answer 2

I've ended up creating two functions to perform this in a more dynamic and scalable way.

    public static TreeNodeCollection SqlToTreeNodeHierarchy(this SqlDataReader dataReader, TreeNode parent)
    {
        // create a parent TreeNode if we don't have one, so we can anchor the new TreeNodes to it
        // I think this will work better than a list since we might be given a real parent..
        if (parent == null)
        {
            parent = new TreeNode("topNode");
        }

        while (dataReader.Read())
        {
            //at the beginning of each row, reset the parent
            var parentNode = parent;

            for (var i = 0; i < dataReader.FieldCount; i++)
            {
                // Adds a new TreeNode as a child of parentNode if it doesn't already exist
                // at this level, else it will return the existing TreeNode and save 
                // it onto parentNode. This way, subsequent TreeNodes will always be a child 
                // of this one, until a new row begins and the parent TreeNode is reset.
                parentNode = AddUniqueNode(dataReader[i].ToString(), parentNode);
            }
        }

        return parent.Nodes;
    }

    public static TreeNode AddUniqueNode(string text, TreeNode parentNode)
    {
        // if parentNode is null, create new treeNode and return it
        if (parentNode == null)
        {
            return new TreeNode {Name = text, Text = text};
        }

        // if parentNode is not null, do a find for child nodes at this level containing the key
        // we're after (text and name have the same value) and return the first one it finds
        foreach (var childNode in parentNode.Nodes.Find(text, false))
        {
            return childNode;
        }

        // Node does not yet exist, so just add a new node to the parentNode and return that
        return parentNode.Nodes.Add(text, text);
    }

Then I just need to call the functions as follows:

using (var sqlConn = new SqlConnection(connectionString))
{
    sqlConn.Open();

    const string query = "SELECT orderDate, customerName from MAIN";

    using (var sqlCommand = new SqlCommand(query, sqlConn))
    {
        using (var sqlDataReader = sqlCommand.ExecuteReader())
        {
            var treeNodeCollection = sqlDataReader.SqlToTreeNodeHierarchy(null);

            foreach (TreeNode treeNode in treeNodeCollection)
            {
                nativeTreeView.Nodes.Add(treeNode);
            }
        }
    }
}

This way I can make it scale with as many child nodes as I want and it also gives me the flexibility of loading the child nodes only when on expand by doing another SQL query and passing the parent as the TreeNode that was just expanded.