public void data_qry(object sender, System.EventArgs e)
{
DataView dv=new DataView();
Table1.Visible=false;
dv=(DataView)Session["dv"];//取得dv
string a="country='"+ txt_country.Text.Trim()+" '";//设定查询语句的字段名等于界面输入的内容
dv.RowFilter=a;//??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
//判断查询记录是否有记录
if(dv.Count>0)
{
Table1.Visible=true;
dv.Sort=drop_index.SelectedItem.Value;
display();
}
}
最有可能的“System.NullReferenceException”类型的异常出现在 bbc.dll 中其他信息: 未将对象引用设置到对象的实例。
{
DataView dv=new DataView();
Table1.Visible=false;
dv=(DataView)Session["dv"];//取得dv
string a="country='"+ txt_country.Text.Trim()+" '";//设定查询语句的字段名等于界面输入的内容
dv.RowFilter=a;//??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
//判断查询记录是否有记录
if(dv.Count>0)
{
Table1.Visible=true;
dv.Sort=drop_index.SelectedItem.Value;
display();
}
}
最有可能的“System.NullReferenceException”类型的异常出现在 bbc.dll 中其他信息: 未将对象引用设置到对象的实例。
{
if(!Page.IsPostBack)
{
SqlConnection conn=new SqlConnection("Server=localhost; User Id=sa; Pwd=vcdvcd; DataBase=Northwind");
conn.Open();
SqlCommand cmd=new SqlCommand();
cmd.Connection=conn;
cmd.CommandText="Select * from Customers";
SqlDataAdapter da=new SqlDataAdapter();
da.SelectCommand=cmd;
DataSet ds=new DataSet();
da.Fill(ds,"Customers");
DataView dv=new DataView();
dv.Table=ds.Tables["Customers"];
dv.AllowDelete=true;
dv.AllowEdit=true;
dv.AllowNew=true;
Session["dv"]=dv;//dv add to session
}
}