错误是“FROM 子句语法错误问题！”错误在第六行！第六行一下的还未运行！
OleDbConnection aConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Application.StartupPath + "/" + "DB.mdb");
            aConnection.Open();///打开数据库
            string SQLString = "select * from user where name='" + textBox1.Text.Trim() + "';";// and password='"+textBox2 .Text .Trim ()+"'";///设置sql 查询语句
            OleDbDataAdapter myadapter = new OleDbDataAdapter(SQLString, aConnection); ///创建适配器，执行sql 查询
            DataSet ds = new DataSet(); ///建立数据集
            myadapter.Fill(ds); ///将查询结果加入 ds 中
             if (ds.Tables[0].Rows.Count > 0) ///判断用名密码是否正确
            {
                OleDbDataAdapter qx_adapter = new OleDbDataAdapter("select qx from user where name='" + textBox1.Text.Trim() + "'", aConnection);
                DataSet ds_qx = new DataSet();
                qx_adapter.Fill(ds_qx);
                qx = Convert.ToInt32(ds_qx.Tables[0].Rows[0]["qx"]);/// textBox4.Text = Convert.ToString(qx);
                form2_01.Show();
                /// form2_01.cdxs(qx);
            }
            else
            {
                ///MessageBox.Show("你按了确定");
                MessageBox.Show("对不起，请输入正确的用户名和密码");
            }
            aConnection.Close();///关闭数据库连接（必须）
            this.Hide();

string SQLString = "select * from user where name='" + textBox1.Text.Trim() + "' and password='"+textBox2 .Text .Trim ()+"'";///设置sql 查询语句

还是没有解决！！！