根据数据库现有数据生成单号

/// <summary>
/// 根据数据库现有数据生成单号
/// </summary>
/// <param name="pDBtran"></param>
/// <returns></returns>
public static string GetNewBillNo(DbTransaction pDBtran)
{
//取得数据
DataSet vds = null;
string vNewBillNo = null;
string SelectBillNo = "select NVL(LPAD(MAX(SUBSTR(BILL_NO,LENGTH(BILL_NO)-3,4))+1,4,'0'),'0001') as Max_NO ";

//构建SQL语句
StringBuilder vsql = new StringBuilder();
vsql.Append(SelectBillNo + "from MOULDING_TESTMOULD where substr(bill_no,3,8)=to_char(sysdate,'yyyyMMdd')");
try
{
DataBaseHelper.ExecuteQuery(true, vsql.ToString(), out vds, null);
vNewBillNo = vds.Tables[0].Rows[0]["Max_NO"].ToString();
}
catch (System.Data.Odbc.OdbcException exp)
{
throw new Exception("New Bill No DataSet 获取 Error ", exp);
}
return vNewBillNo;
}