c# 数据表行计数为空表返回 1

Question

I'm querying a SQL Server database and filling a datatable. But even when my sql returns no values, the datatable row count seems to be one. Here's my code:

strSQL = "My sql string"
cmd.CommandText = strSQL;
cmd.Parameters.AddWithValue("@wsNo", wsNo);
cmd.Parameters.AddWithValue("@reachNo", reachNo);
using (DataTable dt = new DataTable())
    {
        dt.Load(cmd.ExecuteReader());
        MyTextbox.Text = dt.Rows.Count.ToString();
        myGridview.DataSource = dt;
        myGridview.DataBind();
    }

The gridview displays the data correctly, and doesn't display at all if the sql returns no records. But I want to display the record count in a textbox, and that's always 1 when there are no records. A couple of places I've checked imply that ExecuteReader might be the wrong tool for this job, but if so, it isn't clear to me what I should be usi

EDIT: I rebuilt this code using a data adapter, and it seems to be working now. I don't see why, shouldn't make a difference, but I guess rewriting the code fixed whatever I was doing wrong. No further comments necessary. Thanks to people who replied.

Answer 1

Typically you will want to fill your DataSet with DataAdapters. You don't need a DataTable to bring back one record with a DataReader. But here's how you can do it:

DataTable dt = new DataTable("TableName");

using (connection)
{
    SqlCommand command = new SqlCommand(sSQL, connection);
    connection.Open();

    using (SqlDataReader reader = command.ExecuteReader())
    {
        dt.Load(reader);
    }
}

YourControl.Text = dt.Rows.Count;