asp一个代码问题

[wuchao1988]

private string getQueryItem(int index)
{
EasyTool tool = new EasyTool();
string cust_no = "".Equals(selectCust.Text.Trim()) ? "" : string.Format(" AND T.CUST_NO = '{0}' ", selectCust.Text.Trim());
string cust_name = "".Equals(selectName.Text.Trim()) ? "" : string.Format(" AND T.CUST_NAME LIKE '%{0}%' ", selectName.Text.Trim());
string object_name = string.Format(" AND T.TRANSFER_OBJECT = '{0}'", selectObject.SelectedValue.Trim());
string sql = string.Format(@"SELECT T.TRANSFER_OBJECT, T.CONTRACT_NO, T.BILL_NO, T.LOAN_ACCT, T.CUST_NO, T.CUST_NAME, T.ORG_NO, CHAR(T.BEGIN_DATE, ISO), CHAR(T.END_DATE, ISO),
T.LOAN_AMT, A.LOAN_BAL, CAST(T.NORMAL_INTR AS DECIMAL(17,2)), T.DEBIT_INTR + T.DEBIT_INTR_IN + T.DEBIT_INTR_OUT - A.BACK_INTR,
A.LOAN_INTR - A.PAID_INTR, T.LOAN_STAT4, T.LOAN_STAT5
FROM DB2INST1.NONP_LOAN_BASE_INFO T, DB2INST1.NONP_LOAN_ACCT_INFO A
WHERE T.CONTRACT_NO = A.CONTRACT_NO AND T.BILL_NO = A.BILL_NO {0} {1} {2} {3}", tool.getVisiableOrgList("T.ORG_NO", inputOrg.Text), cust_no, cust_name, object_name);//tool.getVisiableOrgList("T.ORG_NO", inputOrg.Text)
string col_en = "TRANSFER_OBJECT,CONTRACT_NO,BILL_NO,LOAN_ACCT,CUST_NO,CUST_NAME,ORG_NO,COLUMN1,COLUMN2,LOAN_AMT,LOAN_BAL,COLUMN3,COLUMN4,COLUMN5,LOAN_STAT4,LOAN_STAT5";
string col_cn = "转让对象,合同号,借据号,贷款帐号,客户号,客户名称,机构,放款日,到期日,贷款金额,贷款余额,正常执行利率(%),核心欠息,CRM欠息,贷款四级状态,贷款五级状态";

里面COLUMN2 我想显示为DB2INST1.NONP_LOAN_BASE_INFO COLUMN2减去DB2INST1.NONP_LOAN_REPAY_INFO REPAY_AMT的值 这个我该怎么写。

[xdashewan]

sql里直接减没有问题的

[wuchao1988]

三表联立吗，能帮忙写下吗