Using 块中的 OleDbCommand：无法使用与其底层 RCW 分离的 COM 对象

Question

仅当我使用 parameters

在 using 块中执行 OleDbCommand 对象时才出现错误 "System.Runtime.InteropServices.InvalidComObjectException: 'COM object that has been separated from its underlying RCW cannot be used.'"

using (OleDbCommand comm = new OleDbCommand())
        {
            comm.Connection = conn;
            comm.CommandType = CommandType.Text;
            string txt = "SELECT* FROM [ListForGroup] WHERE [email] = @email";
            comm.Parameters.Add("@email", OleDbType.VarWChar).Value = userEmail;
            comm.CommandText = txt;
            conn.Open();
            OleDbDataReader reader = comm.ExecuteReader();
            List<ListForGroups> list = returnLists(reader);
            conn.Close();
            cmbSelectList.DataSource = list;
            cmbSelectList.DisplayMember = "listName";
            cmbSelectList.ValueMember = "listForGroupsID";
        }

有谁知道这是为什么。我可以解决它使用 OleDbCommand 对象与 CommandText 没有 parameters 但我读到这是个坏主意。我想在 using 块中进行，以确保所有资源都将被释放。

Answer 1

我解决了这个问题

using (OleDbConnection conn = new OleDbConnection(connString))
    {
        OleDbCommand comm = new OleDbCommand();
        comm.Connection = conn;
        comm.CommandType = CommandType.Text;
        string txt = "SELECT* FROM [ListForGroup] WHERE [email] = @email";
        comm.Parameters.Add("@email", OleDbType.VarWChar).Value = userEmail;
        comm.CommandText = txt;
        conn.Open();
        OleDbDataReader reader = comm.ExecuteReader();
        List<ListForGroups> list = returnLists(reader);

        cmbSelectList.DataSource = list;
        cmbSelectList.DisplayMember = "listName";
        cmbSelectList.ValueMember = "listForGroupsID";
    }

我不知道为什么我没有在 using 旁边的括号中创建 OleDbConnection。另一个解决它的时间是在 using 块之后关闭 connection。

Using 块中的 OleDbCommand：无法使用与其底层 RCW 分离的 COM 对象

OleDbCommand in Using block: COM object that has been separated from its underlying RCW cannot be used

c#

database

using

exception

comobject