Fill: selectCommand.Connection 属性尚未初始化,该如何解决

Fill: selectCommand.Connection 属性尚未初始化

C# code

SqlConnection thisConnection = new SqlConnection(               @"Server=CVRE1WTZRSTAGNW\SQLSERVER2008;Integrated Security=True;Database=gdbranch;");            thisConnection.Open();                       SqlCommand cmd=new SqlCommand();            SqlDataAdapter ada = new SqlDataAdapter();            System.Data.DataTable dataTable = new System.Data.DataTable();                       cmd.CommandText = @"select a.branchid,a.pkey,a.pno,a.ptime,a.pmemo,a.useid,b.pbarcode,sum(qty) from " +                @"pdacheck a inner join pdacheckd b on a.pkey=b.pkey";            ada.SelectCommand = cmd;            ada.Fill(dataTable);            this.dgData.DataSource = dataTable;