OleDbConnection conn = new OleDbConnection();
  
        conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("../web.mdb");
        conn.Open();
        string sql = "select * from admin";

        OleDbCommand cm= new OleDbCommand(conn,sql);
        DataSet ds = new DataSet();
        OleDbDataAdapter da = new OleDbDataAdapter();
      
        da.SelectCommand = cm;
        da.Fill(ds);

        GridView1.DataSource = ds.Tables[0].ToString();
        GridView1.DataBind();




显示错误:
错误    1    与“System.Data.OleDb.OleDbCommand.OleDbCommand(string, System.Data.OleDb.OleDbConnection)”最匹配的重载方法具有一些无效参数    I:\最近\web\admin\admin_gl.aspx.cs    22    26    I:\最近\web\
错误    2    参数“1”: 无法从“System.Data.OleDb.OleDbConnection”转换为“string”    I:\最近\web\admin\admin_gl.aspx.cs    22    43    I:\最近\web\
错误    3    参数“2”: 无法从“string”转换为“System.Data.OleDb.OleDbConnection”    I:\最近\web\admin\admin_gl.aspx.cs    22    48    I:\最近\web\

改为:
string sql="select ....................";
OleDbConnection conn = new OleDbConnection();
conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("../web.mdb");
conn.Open();
OleDbDataAdapter da = new OleDbDataAdapter(conn,sql);
DataSet ds = new DataSet();
da.Fill(ds);
GridView1.DataSource = ds;
GridView1.DataBind();

你的应该改成这样的吧。
OleDbCommand cm= new OleDbCommand(sql,conn);

ls正解……