Question

我正在通过SQL数据适配器填充ComboBox，我遇到了一个问题，即适配器带回了四个表的数量。这很奇怪，因为数据库中只有三个表，并且正在填充最终表（ds.Tables [3]）而不是具有适当行的初始表（ds.Tables [0]）。

以下代码不会填充ComboBox（记下cboCities.DataSource（倒数第二行）：

         private void Form1_Load(object sender, EventArgs e)
    {
        // Establishes a connection to the database.
        SqlCeConnection cn = new SqlCeConnection(@"Data Source = C:\Users\user\Desktop\Projects\ParkSurvey WF\ParkSurvey WF\ParkSurvey.sdf; Persist Security Info = False; Password = *");
        cn.Open();
        // Gathering the names of cities from the Cities database to populate cboCities.
        SqlCeCommand cmd = cn.CreateCommand();
        cmd.CommandText = "SELECT CityId, Name FROM Cities ORDER BY Name ASC";
        SqlCeDataAdapter da = new SqlCeDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        // Closing the connection and setting the data bindings for cboCities.
        cn.Close();
        cboCities.ValueMember = "CityId";
        cboCities.DisplayMember = "Name";
        cboCities.DataSource = ds.Tables[0];
        cboCities.SelectedIndex = -1;
    }

这个DOES适当地填充ComboBox（再次注意cboCities.DataSource）：

        private void Form1_Load(object sender, EventArgs e)
    {
        // Establishes a connection to the database.
        SqlCeConnection cn = new SqlCeConnection(@"Data Source = C:\Users\user\Desktop\Projects\ParkSurvey WF\ParkSurvey WF\ParkSurvey.sdf; Persist Security Info = False; Password = *");
        cn.Open();
        // Gathering the names of cities from the Cities database to populate cboCities.
        SqlCeCommand cmd = cn.CreateCommand();
        cmd.CommandText = "SELECT CityId, Name FROM Cities ORDER BY Name ASC";
        SqlCeDataAdapter da = new SqlCeDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        // Closing the connection and setting the data bindings for cboCities.
        cn.Close();
        cboCities.ValueMember = "CityId";
        cboCities.DisplayMember = "Name";
        cboCities.DataSource = ds.Tables[3];
        cboCities.SelectedIndex = -1;
    }

是什么导致我的DataAdapter带回四个表而不是JUST 城市，为什么它填充第四个表而不是初始表？如果您需要更多代码示例以帮助我解决此问题，请与我们联系。非常感谢你！

Answer 1

如果您填写DataTable而不是DataSet，它应该有效，因为您无论如何只选择一个表。

除此之外，我必须承认不知道这种行为的原因。

当只有3个表存在时，SQL数据适配器返回4个表的计数

1 个答案: