如此判定一个listbox是否绑定?如果已经绑定dataTable如何取消!

Question

private void Button1_Click(object sender, System.EventArgs e)
{
if(ListBox1.Items.Count>0)
ListBox1.DataSource = null;

}

Answer 1

你用一个隐藏textbox,在databind()事件写这个值为已经邦定,在服务端进行取值判断!

Answer 2

sqlDataAdapter1.Fill(dataSet11);
listBox1.DataSource=dataSet11;
listBox1.DisplayMember="TableName.FieldName";
if(listBox1.DataSource!=null)
{
         listBox1.DataSource=null;
if(listBox1.Items.Count>0)
{
for(int i=0;i<listBox1.Items.Count;i++)
{
         listBox1.Items.RemoveAt(i);
}
}
}

Answer 3

if(cboSection.Items.Count>0)
{
                return;
} myOleDbCommand=myOleDbConnection.CreateCommand();
myOleDbCommand.CommandText="select * from sections order by sectionid";
myOleDbDataAdapter.SelectCommand =myOleDbCommand; if (myOleDbConnection.State==0)
{myOleDbConnection.Open();
}

myOleDbDataAdapter.Fill(myDataSet,"sections"); myOleDbConnection.Close();  

myDt=myDataSet.Tables["sections"];
cboSection.DataSource =myDt;

// CboCityName.DataSource=rs.tables(0)
cboSection.DisplayMember="sectionname";
cboSection.ValueMember="sectionid"; cboSection.Items.IndexOf(-1);我现在想让第一个项为空.