如何删除重复的标签页？

Question

如何在C＃Windows窗体中删除重复的标签页名称？我尝试了很多次，它仍然显示标签页上的重复项目。

示例：

我的代码：

SqlCommand cmd = new SqlCommand("SELECT type FROM Products ORDER BY type ASC", con);
con.Open();
try
{
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    da.Fill(dt);
    foreach (DataRow dr in dt.Rows)
    {
        tabControl1.TabPages.Add(dr["type"].ToString());
    }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message, "Error");
}
con.Close();

Answer 1

var cmd = new SqlCommand("SELECT DISTINCT type FROM Products ORDER BY type ASC", con);
con.Open();
try
{
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    da.Fill(dt);
    foreach (DataRow dr in dt.Rows)
    {
        tabControl1.TabPages.Add(dr["type"].ToString());

    }

}
catch (Exception ex)
{
    MessageBox.Show(ex.Message, "Error");
}
con.Close();

Answer 2

您可以使用此功能过滤掉重复的行

public DataTable RemoveDuplicateRows(DataTable dataTable, string columnName)
{
   Hashtable hashTable = new Hashtable();
   ArrayList duplicateList = new ArrayList();

   //Add a list of all the unique item values to the hashtable, which in turn stores a combination of key, value pair.
   //And add duplicate item value in arraylist.
   foreach (var dataRow in dataTable.Rows)
   {
      if (hashTable .Contains(dataRow[columnName]))
     duplicateList.Add(dataRow);
  else
     hTable.Add(dataRow[columnName], string.Empty); 
   }

   //Removing a list of duplicate items from datatable.
   foreach (var dRow in duplicateList)
  dataTable.Rows.Remove(dRow);

   //Datatable which contains unique records will be return as output.
  return dataTable;
}