ASP.NET 建立的Object,判斷空值的问题.
private void btnAddPeople_Click(object sender, System.EventArgs e)
{
//lbDircetList.Items.Add(new ListItem(GetChineseName().ToString(),GetEmployeeid().ToString()));
string sqlstr = " ";
if(ddlAddPeople.SelectedValue == "number ")
{
sqlstr= "select Employeeid From Employees where Number= ' "+txtAddPeople.Text+ " ' ";
}
else
{
sqlstr= "select Employeeid From Employees where ChineseName= ' "+txtAddPeople.Text+ " ' ";
}
SqlConnection myConnection=new SqlConnection(SQLCONNECTIONSTRING);
SqlCommand myCommand=new SqlCommand(sqlstr,myConnection);
myConnection.Open();
object EmployeeidObject= " ";
EmployeeidObject=myCommand.ExecuteScalar();
myConnection.Close();
lblMessage.Text = EmployeeidObject.ToString();
}
问题,如果EmployeeidObject为空值,就会出现 "Object reference not set to an instance of an object. ",提示引用对象.请问怎么解决?谢谢!
[解决办法]
加个判断行么。
myConnection.Close();
if(EmployeeidObject!=null)
{
lblMessage.Text = EmployeeidObject.ToString();
}
[解决办法]
lblMessage.Text = EmployeeidObject==null? " ":EmployeeidObject.ToString();
[解决办法]
> >
lblMessage.Text = (EmployeeidObject == null ? " " : EmployeeidObject.ToString());
[解决办法]
lblMessage.Text = (EmployeeidObject == null ? " " : EmployeeidObject.ToString());
