Question

我有一个列表，当dgv1被填充时，streetId和streetName被填充，在dgv2中我有一个用于streetName的组合框，所以我填充了它的街道，但我有一个cabName cmbxcolumn我需要根据第一列过滤它选择（streetName）.i有一个桌面摄像头：

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

和一个表cabCode：

cabCode  cabName
 19      cabName1
 34      cabName2
 35      cabName3

我在这里尝试过：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;

然后我使用了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());
}

但是当选择一个streetName，例如具有Id 10的streetName1时，过滤器会在cabName组合框中给出三个相同的同名cabcode 19的名称：

cabName3
cabName3
cabName3

我需要过滤它只显示一个名字我觉得过滤有误，是否有人有想法。

Answer 1

是的，应该是因为你的camera表格cabCode = 19重复了3次，而你正在加入，因此产生重复的数据。您似乎可以在此使用ROW_NUMBER()功能

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;

根据列表项

1 个答案: