如何删除重复的标签页？

Question

如何删除C＃Windows窗体中的重复标签页名称？我尝试了很多次，它仍然显示标签页上的重复项目。

例子：

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

就可以过滤掉重复的行使用此功能

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; 
}