how do in write Join query in C#

protected void Button1_Click(object sender, EventArgs e)
        {
            DataSet dsExport = GetData();
            System.IO.StringWriter tw = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter hw =
               new System.Web.UI.HtmlTextWriter(tw);
            DataGrid dgGrid = new DataGrid();
            dgGrid.DataSource = dsExport;

            //Report Header

            // Get the HTML for the control.
            dgGrid.HeaderStyle.Font.Bold = true;
            dgGrid.DataBind();
            dgGrid.RenderControl(hw);

            // Write the HTML back to the browser.
            Response.ContentType = "application/vnd.ms-excel";
            this.EnableViewState = false;
            Response.Write(tw.ToString());
            Response.End();
            //SqlCommand cmd = new SqlCommand("SELECT * FROM [Membermaster] where actuledate between '" + tbfromdate.Text.Trim() + "' and '" + tbtodate.Text.Trim() + "' ", cnn);
        }

        public DataSet GetData()
        {
            DataSet dataSet = new DataSet();
            SqlDataAdapter dataAdapter = new SqlDataAdapter();
            SqlConnection cnn = new SqlConnection("user id=sa;" +
                                      "password=prodip@km;server=PRODIP;" +
                                       "Trusted_Connection=yes;" +
                                       "database=SBT_001;");
            cnn.Open();
            dataAdapter.SelectCommand = cnn.CreateCommand();
            dataAdapter.SelectCommand.CommandText = "SELECT distinct Loanmst.LoanId,'ACTCRD' as SEGMENT_INDETIFIRE,Loanmst.LoanId,Loanmst.LoanId,DB_Name(),(convert(varchar(10),marketmst.MarketId)+'-'+marketmst.Market)'Center Name',EOMst.EOName'RO Name',REPLACE(CONVERT(VARCHAR(10), GETDATE(), 103), '/', '') AS [account_report_date],'JLG' as Loan_category,(groupmst.groupcode+'-'+GroupMst.GroupName)'Group_ID',Loanmst.dose'Loan_Cycle_ID'," +
"LoanPurposeMst.Purpose'Loan_Purpose',Loanmst.Status'Account_Status',LoanApplication.AppDate'Application_date',LoanApplication.SanDate'Sanctioned_Date',Loanmst.LoanDt'Date_Opened',Loanmst.ClosingDt'Date_closed',MAX(CollectionDtLoanmst.RecDate)'Date_of_Last_Payment'," +
"LoanApplication.LoanAppAmt'Applied_for_amount',LoanApplication.ApprovedAmt'Loan_amount_sanction',Loanmst.LoanAmt'Total_amount_disbursed',Loanmst.TotalInstNo'Number_of_Installment',Loanmst.RSchedule'Payment_Frequency',Loanmst.InstallmentAmt'Minimum_amt_due'," +
"Round(LoanAmt -(Select isnull(SUM(PrinCollAmt),0) from CollectionDtl Where LoanId  = Loanmst.Loanid And RecDate <= '02/28/2014'),1) 'Current_Balance'," +
"ROUND((select ISNULL(sum(LoandtLoanmst.Resamt),0) from LoanDtl where LoanId  = Loanmst.Loanid and DueDt<= '02/28/2014')-(Select isnull(SUM(CollAmt),0) from CollectionDtl Where LoanId  = Loanmst.Loanid And RecDate <= '02/28/2014'),1)'Amount_Overdue'," +
"(floor (DATEDIFF(DAY, MAX(CollectionDtLoanmst.RecDate), GETDATE())))'DPD'," +
"(select ISNULL(sum(CollectionDtLoanmst.CollAmt),0) from CollectionDtl where LoanId  = Loanmst.Loanid and RecDate<= '02/28/2014' and DescId='G0023')'Write off Amt'," +
"Loanmst.WriteoffDate'Date_of_writeoff',Loanmst.LWaveOffId'Write_of_Reason','' as'Number_of_Meeting_held','' as'No_of_Absentees_in_Meeting','yes'as'Insurance_Indicator' ,'Cr insurance'as 'Type_of_Insurance' ,Loanmst.LoanAmt 'Sum_assured'," +
"CASE WHEN cr.CollDay = '1' THEN 'MON' WHEN cr.CollDay = '2' THEN 'TUE' WHEN cr.CollDay = '3'THEN 'WED'WHEN cr.CollDay = '4'THEN 'THU'WHEN cr.CollDay = '5'THEN 'FRI'WHEN cr.CollDay = '6'THEN 'SAT'" +
"END as Agreed_Meeting_week_day,cr.Colltime'Agreed_Meeting_day_Time','' as Received_for_Future_Use,''as Old_Member_code,'' as old_member_shrt_name,'' as Old_account_NBR," +
"'' as CIBIL_ACT_STATUS,'' as ASSET_CLASIFICATION,Membermst.memberno 'MEMBER_CODE','' as MEMBER_SHRT_NM,'' as ACCOUNT_TYPE,'' as OWNERSHIP_IND," +
"Membermst.memberno 'PARENT_ID','' as EXTRACTION_FILE_ID,'' as SEVERITY" +
"From LoanMst join MemberMst on (membermst.MemberId=Loanmst.MemberId)" +
"join GroupMst on(MemberMst.GroupId=GroupMst.GroupId)" +
  "join MarketMst on(GroupMst.MarketId=MarketMst.MarketId)" +
  "join EOMst on(EOMst.EOId=MarketMst.Eoid)" +
  "join LoanPurposeMst on (Loanmst.PurposeId=LoanPurposeMst.LPurposeId)" +
  "join LoanApplication on (Loanmst.LoanAppId=LoanApplication.LoanAppId)" +
  "join CollectionDtl on (Loanmst.LoanId=CollectionDtLoanmst.LoanId)" +
  "join CollectionRoutine on MarketMst.MarketId=CollectionRoutine.MarketId" +
  "join CollectionRoutine cr on MarketMst.MarketId=cr.MarketId" +
"Where LoanDt between  '02/15/2014' and '02/28/2014' -- <= '02/28/2014'" +
"And (Loanmst.ClosingDt > '02/28/2014' or Loanmst.ClosingDt is null)" +
"And (Loanmst.WriteoffDate > '02/28/2014' or Loanmst.WriteoffDate is null)" +
"And (Loanmst.TrDate<='02/28/2014' Or Loanmst.TrDate Is Null)" +
"group by Loanmst.LoanId,Loanmst.LoanId,Loanmst.LoanId,(convert(varchar(10),marketmst.MarketId)+'-'+marketmst.Market),EOMst.EOName,(groupmst.groupcode+'-'+GroupMst.GroupName),Loanmst.dose," +
"LoanPurposeMst.Purpose,Loanmst.Status,LoanApplication.AppDate,LoanApplication.SanDate,Loanmst.LoanDt,Loanmst.ClosingDt," +
"LoanApplication.LoanAppAmt,LoanApplication.ApprovedAmt,Loanmst.LoanAmt,Loanmst.TotalInstNo,Loanmst.RSchedule,Loanmst.InstallmentAmt," +
"MemberMst.Membername, Loanmst.memberid,Loanmst.LoanNo,Loanmst.loanamt,Loanmst.dose,Loanmst.loandt,Loanmst.WriteoffDate,Loanmst.LWaveOffId,Loanmst.LoanAmt,cr.CollDay,cr.CollTime,MemberMst.MemberNo" +
"ORDER BY EOMst.EOName,marketmst.Market,GroupMst.GroupName";
 dataAdapter.Fill(dataSet);
 dataAdapter.Dispose();

 return dataSet;               
                
                
                
                
  }

       }
        }