异常：输入数组输入数组长于此表组合框中的列数

Question

为了解释我在做什么，我尝试将特定列中的数据加载到组合框中，为此我使用静态方法。异常跳出以下代码的 7 行。每当我运行程序时，这行就会抛出异常，输入数组输入数组比这个表中的列数长。

void DataGridViewModules()
{
    DataRow dr;
    CommonDBTransaction c = new CommonDBTransaction();
    string sql = "SELECT MId FROM Module";
    DataTable dt = c.searchData(sql);
    dr = dt.NewRow();
    dr.ItemArray = new object[] { 0, "--Select Module--" }; //Exception jumps out here
    dt.Rows.InsertAt(dr,0);
    metroComboBoxMod.ValueMember = "MId";
    metroComboBoxMod.DisplayMember = "MId";
    metroComboBoxMod.DataSource = dt;
}

用于查询数据的静态方法是，

public DataTable searchData(string query)
{
    try
    {
        DataTable table = new DataTable();
        using(SqlConnection con = new SqlConnection(....constring here...))//connection string was added
        {
            using(SqlDataAdapter da = new SqlDataAdapter(query, con))
               da.Fill(table);
        }
        return table;
    }
    catch(Exception ex)
    {
        MessageBox.Show(ex.ToString());
        return null;
    }
}

我做错了什么？我该如何解决它&参考就足够了？

Answer 1

看起来您只在选择查询中检索一列，但您正在向新行添加一个 2 列数组。

你也许可以摆脱以下：

DataRow dr;
CommonDBTransaction c = new CommonDBTransaction();
string sql = "SELECT MId FROM Module";
DataTable dt = c.searchData(sql);
dr = dt.NewRow();
dr[0] = "--Select Module--";
dt.Rows.InsertAt(dr,0);
metroComboBoxMod.ValueMember = "MId";
metroComboBoxMod.DisplayMember = "MId";
metroComboBoxMod.DataSource = dt;

否则，您可能需要为 ValueMember 和 DisplayMember 设置一个单独的列：

DataRow dr;
CommonDBTransaction c = new CommonDBTransaction();
string sql = "SELECT MId AS MId, MId AS DisplayId FROM Module";
DataTable dt = c.searchData(sql);
dr = dt.NewRow();
dr[0] = 0;
dr[1] = "--Select Module--";
dt.Rows.InsertAt(dr,0);
metroComboBoxMod.ValueMember = "MId";
metroComboBoxMod.DisplayMember = "DisplayId";
metroComboBoxMod.DataSource = dt;