当基于列表项的选择过滤组合框时有重复的值

Question

我有一个列表，当dgv1填充时，在dgv2中填充streetId和streetName，我有一个comboboxcolumn列表，因此我填充街道，但是我填充有cabName cmbxcolumn我需要根据到第一列选择（streetName）。我有一个表，照相机对其进行过滤：

camIp cabCode streetId camType camCode 
    11.5 34  9 camtype1 PTZ 
    11.7 34  9 camtype2 C 
    12.1 19  10 camtype2 A 
    12.2 19  10 camtype3 B 
    12.3 19  10 camtype4 PTZ 

和一张桌子cabCode：

cabCode cabName 
19  cabName1 
34  cabName2 
35  cabName3 

这里我已经试过： 我为相机创建了一个数据表：

DataTable CamerastblUsage = new DataTable(); 
SqlCommand cmd5 = cnn.CreateCommand(); 
cmd5.CommandText = "SELECT cam.camIp,cam.cabCode,c.cabName,cam.streetId ,cam.camType,cam.camCode from camera cam , cab c where cam.cabCode = c.cabCode"; 

BindingSource unfilteredCamerasUsageBS = new BindingSource(); 
DataView undv2 = new DataView(CamerastblUsage); 
unfilteredCamerasUsageBS.DataSource = undv2; 
Column23.DisplayMember = "cabName"; 
Column23.ValueMember = "camIp"; 
Column23.DataSource = unfilteredCamerasUsageBS; 

// this binding source is where I perform my filtered view 
BindingSource filteredCamerasUsageBS = new BindingSource(); 
DataView dv6 = new DataView(CamerastblUsage); 
filteredCamerasUsageBS.DataSource = dv6; 

然后我使用的cellbeginedit事件：

if (e.ColumnIndex == Column23.Index) 
{ 
//filter cabCode combobox based on streetId selected in column index 0 
DataGridViewComboBoxCell dgcb = (DataGridViewComboBoxCell)dataGridView3[e.ColumnIndex, e.RowIndex]; 

dgcb.DataSource = filteredCamerasUsageBS; 
this.filteredCamerasUsageBS.Filter = "streetId = " + 
Convert.ToString(this.dataGridView3[e.ColumnIndex - 1, e.RowIndex].Value.ToString()); 
} 

但选择streetName时，例如streetName1具有编号10中，过滤器在cabName comboboxcolumn给出相同cabcode 19三个相同的名称：

cabName3 
cabName3 
cabName3 

我需要过滤它显示只有一个名字，我认为有一个错误的过滤，有没有人有一个想法。

Answer 1

是的，它应该是因为在你的camera表cabCode = 19重复3次，你加入了，所以导致重复的数据。看起来像你可以使用ROW_NUMBER()功能在这里像

SELECT * FROM (
SELECT cam.camIp, 
cam.cabCode, 
c.cabName, 
cam.streetId , 
cam.camType, 
cam.camCode, 
ROW_NUMBER() OVER(PARTITION BY cam.camCode ORDER BY cam.camCode) AS rn 
from camera cam 
join cab c 
on cam.cabCode = c.cabCode) XXX 
WHERE rn = 1;