CODEWITHSUNDEEP
c#
Luis Valencia
Luis Valencia

Reputation: 34008

Merge datatables but ignore duplicated rows

I have the following code, its a custom people picker for sharepoint 2010.

It searches by username, but also by the person name. Because its a contains search, if I try with part of my username: cia

It shows my duplicated rows because that matches the username but also the person name.

this is my code (I cant use LINQ:

 protected override int IssueQuery(string search, string groupName, int pageIndex, int pageSize)
 {
    try
    {
        // Find any user that has a matching name
        var table = ADHelper.ExecuteNameQuery(RootPath, search);

        // 20249: Search by username, method was already done, but it was not being called.
        var table2 = ADHelper.ExecutesAMAccountNameQuery(search);
        table2.Merge(table,);
        PickerDialog.Results = table2;

Upvotes: 3

Views: 15053

Answers (2)

Tim Schmelter
Tim Schmelter

Reputation: 460158

Normally the DataTable.Merge method removes duplicates implicitely. But only when all columns' values are the same.

I'm not sure if there is something simplier(you've mentioned that you cannot use LINQ), but you could merge both and remove the duplicates afterwards:

List<string> dupColumns = new List<string>();
dupColumns.Add("ColumnA");
dupColumns.Add("ColumnB");
table2.Merge(table,);
RemoveDuplicates(table2, dupColumns);

And here the remove-duplicates function:

private void RemoveDuplicates(DataTable table, List<string> keyColumns)
{
    Dictionary<string, string> uniquenessDict = new Dictionary<string, string>(table.Rows.Count);
    System.Text.StringBuilder sb = null;
    int rowIndex = 0;
    DataRow row;
    DataRowCollection rows = table.Rows;
    while (rowIndex < rows.Count)  
    {
        row = rows[rowIndex];
        sb = new System.Text.StringBuilder();
        foreach (string colname in keyColumns)
        {
            sb.Append(((string)row[colname]));
        }

        if (uniquenessDict.ContainsKey(sb.ToString()))
        {
            rows.Remove(row);
        }
        else
        {
            uniquenessDict.Add(sb.ToString(), string.Empty);
            rowIndex++;
        }
    }
}

Upvotes: 9

moustafa malik
moustafa malik

Reputation: 78

you should the .ToTable function

here is a sample code

        DataTable DT1 = new DataTable();
    DT1.Columns.Add("c_" + DT1.Columns.Count);
    DT1.Columns.Add("c_" + DT1.Columns.Count);
    DT1.Columns.Add("c_" + DT1.Columns.Count);

    DataRow DR = DT1.NewRow();
    DR[0] = 0;
    DR[1] = 1;
    DR[2] = 2;
    DT1.Rows.Add(DR);

    DataTable DT2 = new DataTable();
    DT2.Columns.Add("c_" + DT2.Columns.Count);
    DT2.Columns.Add("c_" + DT2.Columns.Count);
    DT2.Columns.Add("c_" + DT2.Columns.Count);
    DT2.Columns.Add("c_" + DT2.Columns.Count);

    DR = DT2.NewRow();
    DR[0] = 0;
    DR[1] = 1;
    DR[2] = 2;
    DR[3] = 3;
    DT2.Rows.Add(DR);

    DT1.Merge(DT2);
    Trace.IsEnabled = true;
    DataTable DT_3=DT1.DefaultView.ToTable(true,new string[]{"c_1","c_2","c_0"});
    foreach (DataRow CDR in DT_3.Rows)
    {
        Trace.Warn("val",CDR[1]+"");//you will find only one data row
    }

Upvotes: 1

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