Filtering DataView with multiple columns

问题

In my application I am using a dataview for having the filters to be applied where the filter options are passed dynamically.if there are 2 filter parameters then the dataview should be filtered for parameter1 and then by parameter two. I am using a method which is called in a for loop where I am setting the count to the total no.of parameters selected using a listbox but the filtering is done only for the last parameter. Here is my code:

string str = "";
for (int i = 0; i < listbox.Items.Count; i++)
{
    if (listbox.Items[i].Selected)
    {
        if (str != string.Empty)
        {
            str = str + "," + listbox.Items[i].Text;

        }
        else
        {
            str = str + listbox.Items[i].Text;
        }
    }
}

string[] items = str.Split(',');
for (int i = 0; i < items.Length; i++)
{
    ApplyFilter(items[i],dv);
}

private DataView ApplyFilter(string str,DataView newdv)
{
    newdv.RowFilter = "[" + str + "]=" + ddl.SelectedItem.ToString();

    return newdv;
}

Please provide a suitable solution .

Thanks in advance...

回答1:

You should apply your filter altogether, not one by one :

newdv.RowFilter = "Column1 = " + value1 + " AND Column2 = " + value2;

So you can change your code as :

string[] items = str.Split(',');
string filter = string.Empty;
for (int i = 0; i < items.Length; i++)
{
    filter += items[i] + " = " + dropdown.SelectedValue;
    if (i != items.Length - 1)
    {
         filter += " AND ";
    }
}
newdv.RowFilter = filter;

回答2:

I think you should build a complete filter string and then set this filter to your DataView. For example:

StringBuilder sb = new StringBuilder()
for (int i = 0; i < listbox.Items.Count; i++) {
  if (!listbox.Items[i].Selected) {
    continue;
  }

  if (sb.Length > 0) {
    sb.Append(" and ");
  }
  sb.AppendFormat("[{0}] = {1}", listbox.Items[i].Text, ddl.SelectedItem);
}

dv.RowFilter = sb.ToString();

回答3:

DataView dv = new DataView(dt);
string filterText = "some search criteria";
dv.RowFilter = "Column1 + Column2 + Column3 Like '%" + filterText  + "%'";

回答4:

I had a similar problem - but i think solution will be the same for both of them. I have a datatable that needs to be filtered by 5 controls and if they aren't filled - it shouldn't be filtered.

List<string> allParams = new List<string>();
//here add fields you want to filter and their impact on rowview in string form
if (tsPrzelewyTxtOpis.Text != ""){ allParams.Add("Opis like  '%" + tsPrzelewyTxtOpis.Text + "%'"); }
if(tsPrzelewyTxtPlatnik.Text != ""){ allParams.Add("Płacący like  '%" + tsPrzelewyTxtPlatnik.Text + "%'"); }
if(tsPrzelewyDropDownKonto.Text != "") { allParams.Add("Konto =  '" + tsPrzelewyDropDownKonto.Text + "'"); }
if (tsPrzelewyDropDownWaluta.Text != "") { allParams.Add("Waluta =  '" + tsPrzelewyDropDownWaluta.Text + "'"); }
if (tsPrzelewyDropDownStatus.Text != "") { allParams.Add("Status =  '" + tsPrzelewyDropDownStatus.Text + "'"); }

string finalFilter = string.Join(" and ", allParams);
if (finalFilter != "")
{ (dgvPrzelewy.DataSource as DataTable).DefaultView.RowFilter = "(" + finalFilter + ")"; }
else
{ (dgvPrzelewy.DataSource as DataTable).DefaultView.RowFilter = ""; }

来源：https://stackoverflow.com/questions/1137020/filtering-dataview-with-multiple-columns