[英]dropdown selected index changed event fires while setting data from database in asp.net c#
[英]C# windows forms listbox selected index changed event fires on form load and button click
我正在编写一个程序,允许用户使用客户名称搜索客户订单,用户在TextBox
键入名称,搜索结果显示在ListBox
控件中,用户必须从列表中选择名称框和客户的订单显示在DataGridView
,问题是客户点击SelectedIndex
更改事件后触发的搜索按钮并导致程序崩溃。
private void btnSearch_Click(object sender, EventArgs e)
{
string Query = "SELECT CustomerID, CompanyName FROM Customers WHERE (CompanyName ”+ “LIKE'%"+ txtSearch.Text + "%')";
clsDataTools.cmdComand = clsDataTools.con.CreateCommand();
clsDataTools.cmdComand.CommandText = Query;
clsDataTools.dtaDataAdapter = new SqlDataAdapter();
clsDataTools.dtaDataAdapter.SelectCommand = clsDataTools.cmdComand;
dsOrdersByCusName = new DataSet();
clsDataTools.con.Close();
clsDataTools.con.Open();
clsDataTools.dtaDataAdapter.Fill(dsOrdersByCusName);
clsDataTools.con.Close();
dsOrdersByCusName.Tables[0].TableName = "OrderBCusName";
lstResults.DataSource = dsOrdersByCusName.Tables[0];
lstResults.DisplayMember = "CompanyName";
lstResults.ValueMember = "CustomerID";
}
private void lstResults_SelectedIndexChanged(object sender, EventArgs d)
{
string Query = "SELECT * From Orders WHERE CustometID = '"
+ lstResults.SelectedValue
+ "'";
dataGridDataSet = new DataSet();
clsDataTools.dtaDataAdapter = new SqlDataAdapter();
clsDataTools.cmdComand = clsDataTools.con.CreateCommand();
clsDataTools.cmdComand.CommandText = Query;
clsDataTools.con.Close();
clsDataTools.con.Open();
clsDataTools.dtaDataAdapter.SelectCommand = clsDataTools.cmdComand;
clsDataTools.dtaDataAdapter.Fill(dataGridDataSet);
clsDataTools.con.Close();
dataGridDataSet.Tables[0].TableName = "Orders";
dgvCusOrders.DataSource = dataGridDataSet;
dgvCusOrders.DataMember = dataGridDataSet.Tables["Orders"].ToString();
}
我真的不明白为什么当我点击搜索按钮时会引发SelctedIndexChanged
事件是否有我可能遗漏的东西?
由于您设置了lstResults
的数据源,因此它将调用SelectedIndexChanged
,您可以执行以下操作
private void btnSearch_Click(object sender, EventArgs e)
{
//Remove the handler
this.lstResults.SelectedIndexChanged -= lstResults_SelectedIndexChanged;
//
// Your code
//
this.lstResults.SelectedIndexChanged += lstResults_SelectedIndexChanged; // Add the handler
}
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